454 Tbi High Idle

This can be magnified by not having enough torque converter stall rpm and to a lesser extent not enough rear gear ratio. But sometimes. the gauge should be still the same psi. Preventives. I recently picked up a 95 suburban. 93' K5 Blazer 5. will not turn it over. You cannot adjust the idle speed with a setscrew or any other mechnical adjustment. 1988 454 with Quadrajet carb. Hi, I am having a problem with my chevy 350 engine that I just installed back in August. Note: The above applies only to U. The holley part # 502-20S, is a 670cfm TBI with 85 lb injectors. Every year brought issues with it and that high idle cold start eats a gallon of gas before even leaving the driveway. chevy forum at Car Dealer Forums; I have an '86 GMC 1/2 ton pick-up that now has a 5. Base idle cap had never been tampered with prior to me removing it, I made sure the blades were fully closed by turning the screw back, nothing changed. 3L TBI V6 from a salvage yard. It has the TBI gm fuel injection, which they had just came out with at that time to replace the carb. Direct shipping means you get it fast and our experienced new engine center employees know most of the accessories that you may need to finish your repower or new engine installation. chevy tbi base idle adjustment P0507 Idle Control System (RPM Too High) - vacuum. The holley part # 502-20S, is a 670cfm TBI with 85 lb injectors. Any adjustments made to the idle speed, should be followed by adjusting your throttle position sensor (TPS). Just low idle at 400rpm and has a slight stutter. I need more fuel pressure anyways and then I will have the piece of mind knowing that the TBI gaskets are new and the Throttle body has been rebuilt. Cranking and Idle. I've replace just about every electronic item on the engine (preventative maint). If it's a TBI 454 the Distributor Advance wire you're looking for is against the firewall on the passenger side kind of by the A/C stuff. Hi i am new to this forum and in desperate need of advice. I have checked for leaks and it doesnt have any. You may have to register before you can post: click the register link above to proceed. " If turning the ignition on causes IAC to engage plunger fully forward, then there is no purpose in doing what he is suggesting. What a difference! Much more air off idle and way more air at WOT!!!. back to the tank or in the engine. could not tell you why idle is high. I put a new trans in it (2600. I also don't recommend a 454 TBI unit as they were designed to idle big block engine and often cause idle and light throttle fuel control issues on SBC so save yourself and me some headaches and get a bored SBC throttle body. I am getting around 8 miles to the gallon and my fuel trim is around 90 at idle. I live in western Canada, and have since made several trips into the rockies. This is a discussion on [SOLVED] extream high idle problem on 1990 chevy 1500, 4. Is the tps adjustable. when my truck is idleing it will start to idle super fast to fast to put in gear. Big array of lt1 350 tbi at competitive prices. Cleaning and Resetting Your Idle Air Control (IAC) Valve Posted On : February 11, 2018 Published By : admin [sswfb_post_share] What you will need for the following procedure is carburetor cleaner and a wrench big enough to remove the IAC valve. Next I reinstalled the throttle body, fired it up and it fired right up. We will see how this compares to what the “target idle speed” is set at in the chip. 2003-2004 Dodge - $1,895. I have taken it to a half a dozen mechanics, promising me that they could find the problem. 7 TBI Cold start flooding issue Hey gang new here and in need of some help. Its only at warm idle. Carbon Monoxide is a by-product of incomplete combustion. Over all good system BUT one thing I noticed was that there was a flat spot in the throttle near full throttle. As the engine warms, the IAC counts should decrease. 3 Measure using an accurate service tachometer with engine at normal operating temperature. Find Crusader In Stock Now. INSTALLATION OF PRODUCTION GM AND 670 CFM 2 BARREL THROTTLE BODY FUEL INJECTION KITS ON FORMERLY CARBURETED ENGINES. The chevy 454 is in a 1988 sportscoach pathfinder rv. Text HELP to 773929 for additional info. The Performer 454 TBI manifold delivers outstanding performance for the street with complete emissions compatibility. I've been working on catching up some maintenance and a few things the PO had let go. In fact, the old O2 sensor was one of the first ever used to electronically modulate the ratio of fuel and air used by the engine -- in a time even before what we would recognize as fuel injection today even existed. even moving the idle screw a HAIR belowim talking maybe 1/8th of an inch of turnthe engine sputters and starts to die. Turn the ignition ON and leave on for several seconds then turn the ignition OFF to allow the ECM to reset the IAC valve. 3HP Search Maritime Propulsion Jobs. com is a division of Guaranteed Carburetors of Largo, Florida. I checked my connections and verified grounds and tried it again. The idle quality should still be close to stock. Note: The above applies only to U. Seems like I got all of them fixed except one. Idle-5500 RPM Power! The Chevrolet TBI (throttle body injection) Performer manifolds are dual-plane, low-rise intake manifolds with a 180° firing order and a patented runner design that delivers outstanding performance with crisp throttle response. I have a 94 454 TBI and was chasing what i thought was a high idle. Chevy Blazer idle is too low, then when come to a stop is very high for a few seconds. Again, runs smooth at idle and even Revs smoothly but only when the truck is in park. When i first start the truck it slowly rises from 1000 to 1500 rpm then comes down after five minutes to 1000 rpm then when i drive it for a few minutes then it starts idling at 1100 rpm when the truck is in drive. I have read almost every article and threads on the Internet about this problem, but haven't found a working solution for my setup. 7l Brand New Fuel Injection Idle Air Control Valve For Chevy Gmc Hummer Efi Complete. Aside from high idle issues, low idle and even sporadic stalling can both be attributed to a bad idle control valve. I've got a miss and hessitation when accelerating. replaced sensors and cleaned carbon from throttle did not help. Ive got a 95 K3500 Silverado, I bought it with about 151K on it, and it had a blown trans. With the factory cam, it idled perfectly at the 650/750 rangeand i bought the thumpr cam specifically for that low lopey idle, and am disappointed that for whatever reason, it wont stay running below 1k. 4 barrel tbi installation page 1 installation of howell engine developments high performance 2 & 4 bbl throttle body fuel injection on engines originally equipped with carburetors this system is based on the production gm (chevrolet) throttle body fuel injection system and electronics used from 1987-91, on 305, 350, and 454 v-8 engines. With the IAC passage completely plugged the engine should barely be able to idle, fully warmed up with all accessories off. It went thru the high idle step untill it warmed up and then it. #2 make sure your TBI base gasket didn't get sucked in. What happens if the MAP sensor is bad on my 1991 2500 454 TBI Suburban? What effects will be noticed. Listed below is a group classification for the custom (or high) performance camshafts listed in this catalog – (the durations shown are based on. com is a division of Guaranteed Carburetors of Largo, Florida. Check and repair all defective cracked vacuum lines. Hi, I am having a problem with my chevy 350 engine that I just installed back in August. The TBI injectors are getting a good signal and I can watch the pulse and inject fuel in the start mode and immediately peter out in the idle mode. Check the vacuum advance because if it is not working the timing could be too far advanced and the diaphragm may have a air leak creating a lean mixture. We specialize in a wide-variety of high-quality car parts and accessories for your car, truck or SUV. I believe the factory idle is set to 800 rpm, something to keep in mind. 4 A special procedure must be followed to check or adjust timing. Within about 50 miles of home topped off (half tank) with 89 octane to see if it would help. This is available in single and twin engine applications. Since 1938, Edelbrock has manufactured its core products in the USA for quality & performance. Check and make sure the air. Alt is working well. You'll find an extra 20HP here. 8 Chevy 60-Degree V6 parts in-stock with same-day shipping. Anywaydid you actually try mashing it down and releasing it to get the choke off? Sounds about right, you put a load on it by putting it in gear, the idle fellif you take your foot off the brake it'll probably do about 25mph (at least our 454 does on high idle). High Strength Steel Dim Lights At Idle. INSTALLATION OF PRODUCTION GM AND 670 CFM 2 BARREL THROTTLE BODY FUEL INJECTION KITS ON FORMERLY CARBURETED ENGINES. I also don't recommend a 454 TBI unit as they were designed to idle big block engine and often cause idle and light throttle fuel control issues on SBC so save yourself and me some headaches and get a bored SBC throttle body. The high idle may be that the carburetor idle kick down is not releasing properly. However, idle vacuum was 18. Edelbrock is the most respected name in performance. I let the truck run for a while and it never idled down. I've quite a bit of experience with old cars and trucks but the newer ones (yes, even 1987) give me trouble. One interesting note: isolated the IAC problem by plugging the air horn intake path to the valve, resulting in a corresponding drop in idle. NOTE: Vacuum readings will vary according to the altitude in different localities. 454 Engine missing and cutting out under load HELP PLEASE Just the other day out of the blue it starting missing bad under a load. Trouble Code 25 indicates that the Manifold Air Temperature sensor is reporting abnormally high readings. 7l engine with tbi. What happens if the MAP sensor is bad on my 1991 2500 454 TBI Suburban? What effects will be noticed. One tan and one black. Compare prices of Spread Bore and other comparable products. 4 barrel tbi installation page 1 installation of howell engine developments high performance 2 & 4 bbl throttle body fuel injection on engines originally equipped with carburetors this system is based on the production gm (chevrolet) throttle body fuel injection system and electronics used from 1987-91, on 305, 350, and 454 v-8 engines. Didnt want to idle normally, the rpms changed. 3 v6 TBI within the Automotive Support forums, part of the Tech Support Forum category. Setting IAC (Idle air control) valve I saw this video , and wonder about his words of "wisdom. I also don't recommend a 454 TBI unit as they were designed to idle big block engine and often cause idle and light throttle fuel control issues on SBC so save yourself and me some headaches and get a bored SBC throttle body. If the idle is low and inconsistent, it may be due to an issue with your idle control valve. Every year brought issues with it and that high idle cold start eats a gallon of gas before even leaving the driveway. 1992 Chevy 454 7. idle speed" is. It had slightly reduced power compared to the L29 454 and used a different PCM. It determines the fuel pressure achieved at full throttle. Text STOP to 773929 to can. Will the regulator help the truck idle better?The cam is a cc 294 hydraulic roller. 47,000 miles in a motor home. ) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!. (fast idle control device) valve. 4L VIN N TBI. When I check after the car has sat overnight (ATF cold) and engine not on, it reads a little high (above the Full Hot mark). I am working on a truck for the inlaws. If the fast idle just came on, I would first check the TBI mounting plate for a leak due to it's possible deterioration. Holley 670 cfm or GM 454 2 bbl TBI. I checked for a code , got 24 vehicle speed sensor, I don't think that would mess with the idle would it ?. When i first start the truck it slowly rises from 1000 to 1500 rpm then comes down after five minutes to 1000 rpm then when i drive it for a few minutes then it starts idling at 1100 rpm when the truck is in drive. Replaced: Plugs Wires Cap Rotor Coil Coolant temp sensor Cleaned pcv,egr and checked for vacuum leaks Adjusted/advanced timing Removed cat Still have rough idle, and slight smell of unburnt fuel. 4l tbi P30 Exhaust Manifold Glowing Cherry Red HOT If the TB pintle is fully seated as in 0 counts then theory says the engine should not idle. What grouping or type of intake should I be looking for?. Self taught, barely backyard mech status, for the love of the game. He told me that he had the problem with a car powered by 454 several years ago. I have it in pretty good shape except for the idle. 7 EFI 350 MAG MPI 6. 7L, TBI, 260K on the motor at idle, it's extremely high, around 1600-1800 RPM's when put it drive, drops down to about 1000-1200 (still way too high) I've put a new IAC (idle air control) valve in, checked my timing. It idles terribly. Boat Parts and Accessories Store Find Replacement Boat Parts, Electronics, Navigation, Engines, Fishing Supplies, and more. I have a 94 454 TBI and was chasing what i thought was a high idle. If you need to adjust your minimum air (idle speed), click here. I have a 91 Chevy k1500 4x4 p/u with a idle issue. Disconnect the distributor vacuum advance and plug the line. Also, if I put it in park, the engine will idle down somewhat but when I put it in gear the engine will stutter for a few seconds and then idle up again. 89 454 tbi cold weather no start Trash Or Be Trashed. But first, a word on prevention. 4L (454) Custom Tuning Part# UP74 If you will be sending us your ECM for reprogram you do not need to select core charge but if you are wanting us to program and send you a computer you must choose the core charge. Engines covered: Pre-Optispark small block Chevy V8s with TPI or TBI injection and HEI ignition with electronic spark timing (seven or eight pin HEI module) Much of this article will apply to other 1980s era GM cars including injected big blocks and even fire V6s. even moving the idle screw a HAIR belowim talking maybe 1/8th of an inch of turnthe engine sputters and starts to die. However, idle vacuum was 18. 2 MPI Horn Output Possible Cause Corrective Action Engine Usage Available For Consumer Key on, beep for 2 seconds, then off. Our OEM Throttle Body Injection (TBI) Assemblies are complete and ready to install. Made the idle surge or just higher at times depending on what mood the TPS was in. 350 small block knock at idle rpms i have a chevy 350 small block that knocks at idling rpms. I have a 91 jimmy with the 4. It went thru the high idle step untill it warmed up and then it. This kit is the right choice if your vehicle is already fit with a high pressure electric fuel pump, regulator and return line. Both of these speeds are too high for idle. in the chilton book it tells you idle is autmaticly adjusted through the computer so thers not a hell of alot you can do it about it but it says if absolutely needed you can remove this seal behind the stop screw. Just set the idle as if you were in drive and then adjust the timing to the factory-specified timing mark. I have a new GM p/n 17113186 vacuum compensated fuel pressure regulator in box. Personally on my "good" big blocks I run 15w-40 in the summer and 5w-40 in the winter, but on most of them I just run whatever I get for a $1 a qt in my stash. #2 make sure your TBI base gasket didn't get sucked in. You'll find an extra 20HP here. I have it in pretty good shape except for the idle. I have a rough/high idle issue. to fuel pressure regulator)1597cc 1989—90 34 (w/o vac. 800-900 in gear. Ive got a 95 K3500 Silverado, I bought it with about 151K on it, and it had a blown trans. As I have it set right now, my idle at park is in the high 700s and my desired idle in gear is set at about 700 cold (80 degrees) and gradually lowers to 590 once engine temp reaches 160 degrees. 5 when at idle. A soccer mama will need added seating for carpooling as well as great deals of area for sports tools, while a bachelor or bachelorette could appreciate a high street sportscar for whizing around town as well as effortlessly auto parking in limited rooms. 1995 K3500, (454), Computer commanding high idletoo high Discussion in ' Engine Performance + Maintenance ' started by 454/4X4 , Jun 25, 2013. One tan and one black. Idle Learn MAX = This is the maximum number of steps that can be learned up. This way, when low throttle input was used, low power output is produced. to fuel pressure regulator)1597cc TBI 1987—88 14 2389cc (early) 1986 14 2389cc (late) 1986—89 36 2960cc TBI 1986—89 36 All 2V 1985—87 2. This is usually just a normal oxygen sensor that is a little more linear in its behaviour away from the 14. · Calibrated PROM exclusively for 455 or 403 engines. 1volts at idle. There is the basic self learning group of TBI - they have the advantages you mentioned and the modern setups work well, especially if you have a tame cam and lots of idle vacuum. This Edelbrock cam kit produced 540 HP & 530 ft-lbs. There is no needle valve, check valve, or restrictor included with the 2023. But NO ONE, and this includes the Chevy dealer, could find the problem. 3 out of 5 stars 26 $39. The middle group would be tuneable TBI. 2003-2004 Dodge - $1,895. See our Manifold And Carb Kits, Ford Chevy Pontiac Chrysler Edelbrock is the most respected name in performance. Canadian Chevy/ GMC. Thought I had a problem with gas, changed fuel filters, had fuel pump checked and added Sea Foam. 93' K5 Blazer 5. It had slightly reduced power compared to the L29 454 and used a different PCM. I have a 1993 P30 with a 454 in it. Next I reinstalled the throttle body, fired it up and it fired right up. I've had difficulty controling my idle every since i've owned the vehicle, even before the rebuild; and i've tested/replaced about everything that you've mentioned. Exclusive Content. Testing on our 454 showed 15. The chevy 454 is in a 1988 sportscoach pathfinder rv. 3 liter S10 idle problem? So when I start it up it idles from 1500 to 2000 rpms in park or neutral. For sale is a stage 3 complete engine rebuild kit for 1987-1995 Small Block Chevy 350 TBI Engines. 454 Big Block Chevy Turn-Key Crate Engine With 550 HP GM performance Gen VI 454 4 bolt main Chevy block Block painted with 3 coats of high temp ceramic engine paint customer's choice of color. The engine runs fine when cold but as it warms up it starts to "surge" at idle and when you come to a stop it acts like it wants to stall then it grabs. The Edelbrock 7162 powerband ranges from 1,500 to 6,500 rpm, and they maintain a 10” to 12” vacuum during idle. 7L) engines. You are currently viewing our community as a guest which gives you limited access to view most discussions and access our other features. Each car has a unique IAC value that takes into account the condition of the sensors, air and vacuum passages, etc. Once up to speed, at a steady 35 MPH on the flat and level there is noticable surging (not as bad as before replacing the MAP vacuum link hose). I have a 96 1500 5. The pcm is located next to the master cyl unlike my K1500 which is near the glove box. but there is an adjustment. If the fast idle just came on, I would first check the TBI mounting plate for a leak due to it's possible deterioration. 5 -12 at idle which is too rich and I am trying to figure out why and what to do about it. Extra air getting in the engine will speed up the idle. 3 out of 5 stars 26 $39. Re: 454 Chevy temp sensor 01/18/2016 12:50 AM In the first design of the 366-427 engine, all coolant monitoring was done by water temperature sensors installed in the intake manifold in the short water runners between the thermostat housing, and the front of the cylinder head. GM TBI fuel pressure spec. 1985-92 TPI Set Timing and Idle Procedure: SET TIMING 1 Use standard, accepted procedure to confirm Top Dead Center (TDC) of #1 piston agrees with 0 on timing mark. 7L 350 V8 in the alt. You cannot adjust the idle speed with a setscrew or any other mechnical adjustment. Hi, I am having a problem with my chevy 350 engine that I just installed back in August. Only a few 30/35 series chassis cab models offered carbureted 292, 350 and 454 engines, and those were the only models that did not use catalytic converters for 1987 on. Msg & Data Rates May Apply. The pressure regulator on a TBI 220 unit is serviced as a part of the meter cover and should not be disassembled. If this is the case, the engine will idle high when out of gear and then the idle speed will drop down once it's put in gear, and the off-idle response will be poor. the check engine light was on all the way but it ran great. Idle air control valves open to allow more air to "leak" into the intake, raising the engine rpms, or close when not needed. 2 Disconnect Timing Jumper at distributor (Tan wire with Black stripe). Extra air getting in the engine will speed up the idle. But if after testing, it is determined that you need a engine, We can take care of you at our facility. Edelbrock Performer 454 TBI Intake Manifolds in-stock with same-day shipping. Starts up, high idle comes on and than goes down. MCM/MIE GM V-6 and V-8 (305, 350, 454 and 502 cid) EFI engines Symptoms of a failed IAC can be rough idle, fluctuating idle, engine stalls when coming down from full throttle, hard to start or high rpm on start › See more product details. With the factory cam, it idled perfectly at the 650/750 rangeand i bought the thumpr cam specifically for that low lopey idle, and am disappointed that for whatever reason, it wont stay running below 1k. Starts up, high idle comes on and than goes down. I have it in pretty good shape except for the idle. MoPar did this trick back in the early emissions days. ThrottleBodyInjection. The TPS itself is simply a linear variable resistor that when driven by the ECU produces a linear voltage in a 0-5 volt range, 0 volts being idle and up to 5 volts representing. Generic TBI Fuel Injection Block Diagram & Acronyms Individual Components and Their Function We have covered the block diagram and acronyms and are now ready to take a look at the function of the individual components, and some general information about them, and how to procure them. 4 barrel tbi installation. 4L (454) Custom Tuning Part# UP74 If you will be sending us your ECM for reprogram you do not need to select core charge but if you are wanting us to program and send you a computer you must choose the core charge. ECM (computer) will not have a problem with this at all. News: 73-87chevytrucks. The local shop said they replaced it, but it doesn't look new. There is the basic self learning group of TBI - they have the advantages you mentioned and the modern setups work well, especially if you have a tame cam and lots of idle vacuum. Misfires can occur at idle, when the engine is pulling hard under load, at high rpm and during throttle transitions as the air/fuel mixture changes. 7L engines is shown on the right. 70 seconds (includes manifold #350-3764, cam kit #350-2162 and Tubular Exhaust System). On a normal operating engine, it is typical to see high IAC counts (100 or more) when the engine is idling cold and during the warm-up cycle. However, if throttle body is replaced AND a proper idle speed cannot be obtained, there is an adjustment which may be made. Choose top quality brands AC Delco, API, Delphi, Forecast, Replacement, Standard Motor Products, Walker. good k&n replacement air filter in the stock air cleaner , leave the tube that goes to the fender off. 8 Chevy 60-Degree V6 parts and get Free Shipping on orders over $99 at Speedway Motors, the Racing and Rodding Specialists. Before it would idle around 800 to 1,000 rpm, after installing the idle was 1,500 to 1,800 rpms. Will the regulator help the truck idle better?The cam is a cc 294 hydraulic roller. The Basic Kit provides; the Throttle Body, Power Module, Wide-Band 02 Sensor, harnesses and the Handheld Programmer. We’ve seen this. I am getting 3 codes 67, 53, and 32. While driving if you. I would recommend you reuse the OLD SPRING and not use the Hi-Po one they send. The Y45-2 Rochester Marine Throttle Body Injection (TBI) is OEM original marine equipment. All TBI assemblies are flow bench tested, calibrated and idle adjusted which makes for easy installation. · GM ECM used in 1987-92 trucks. i have misted around the intake with starting fluid with no change as if a vaccum leak would turn up. Find 1995 CHEVROLET 7. May just need a new pump. It would down shift into 1st. As with many high performance engines during the muscle car wars, there were lots of rumors flying around in regards to actually how much horsepower the 454 engines put out as opposed to what Chevrolet was reporting. No engine fires every cylinder 100% of the time. 1) To me, its dumb to have it idle so high if it still is going to stall when dropped in gear, 2) My first thought is that the cam has too much duration & overlap, and this is why its stalling at anything below 950 rpm. and gives the engine a distinctive idle that sounds really cool. Connect the distributor vacuum hose and position the fast idle cam follower on the top step of the fast idle cam (turn air conditioning off) and adjust the fast idle to 1,300 rpm on manual transmission 350 engines; 1,600 rpm for all automatics in Park. Isn't idle controlled by the ECM on your (TBI?) injected motor? It could be caused by a faulty sensor (maybe ECT?) but I'm thinking you might try swapping the Idle Air Control valves to see if the issue follows the parts. Aside from high idle issues, low idle and even sporadic stalling can both be attributed to a bad idle control valve. I need more fuel pressure anyways and then I will have the piece of mind knowing that the TBI gaskets are new and the Throttle body has been rebuilt. The engine runs fine when cold but as it warms up it starts to "surge" at idle and when you come to a stop it acts like it wants to stall then it grabs. Problem: With the engine running at idle, always when cold, intermittent when hot. · New ECM wiring harness. Replacement Idle Air Control (IAC) Motor for Sniper EFI TBI Systems, Sniper 90/92/102mm Throttle Bodies, Terminator TBI, Avenger 4bbl TBI, HP 4bbl TBI, Commander 950. 454 Big Block Chevy Turn-Key Crate Engine With 550 HP GM performance Gen VI 454 4 bolt main Chevy block Block painted with 3 coats of high temp ceramic engine paint customer's choice of color. (fast idle control device) valve. The reality is a little more complex. Just installed a new 350 crate engine with a rebuilt TBI. In fact, the old O2 sensor was one of the first ever used to electronically modulate the ratio of fuel and air used by the engine -- in a time even before what we would recognize as fuel injection today even existed. it idles fairly ok when its warmed up but when its cold it idles like crazy. i have misted around the intake with starting fluid with no change as if a vaccum leak would turn up. 7L engines is shown on the right. Please include TBI number (location of number is circled below) and enter all the required information about your TBI and Boat in the text boxes below. All backup systems. Had one of them not been a TBI Guru, I probably would have stuck w/ the pane. Past approx 1/4 throttle angle the deflector side of the throttle body will start allowing air thru. 4L V6 TBI Throttle Body Intake/Butterfly Valve Housing Pre-Owned. We’ve put together this quick-guide to reading your vacuum gauge to help you identify potential mechanical or tuning issues more quickly. I changed the iac valve three times and checked for vacuum leaks several times. the engine is an 86. I have a 1995 chevy p30 18' box truck with a 7. 1volts at idle. Next step up would be a set of cast iron Vortec Heads ($259 each brand spankin' new) and a GMPP TBI intake manifold (another $250) to fit the new heads and TBI unit. the engine is an 86. But sometimes. Just not running right. it idles fairly ok when its warmed up but when its cold it idles like crazy. 350 small block knock at idle rpms i have a chevy 350 small block that knocks at idling rpms. I am getting around 8 miles to the gallon and my fuel trim is around 90 at idle. Found no leaks around TBI, intake manifold and all vacuum lines. The iac on my 454 tbi unit is held on with two screws and has a flat 4 wire connector, identical to the plug on the ignition module. runs rough and feels starved for fuel when in drive and under any sort of load, barely drivable. 6mm or about 1/16 inch longer than most replacement fuel injectors for the GM 7. 7 tbI I have replaced every sensor on motor had igniton timing redone. All 2023 adjustments are made at idle with the signal line removed. The early systems from 1982-1986 are just too old to do much with. Sbc Chevy 350 400 Polished High Rise Aluminum Single Plane Intake Manifold. The TBI injectors are getting a good signal and I can watch the pulse and inject fuel in the start mode and immediately peter out in the idle mode. The stock spring is alittle 'softer' and the range from idle to WOT isn't so dramatic. Posted By: Rockwood27 on 05/13/07 05:25pm My '90 MH on above chassis always has a high idle, even after the engine is warmed up. So you're setting a base idle in case IAC/ECM failure so you can use brakes. (No Trucks) - 88 chevy truck popping through tbi - 88 chevy 1500 5. Cranking and Idle. The middle group would be tuneable TBI. It would down shift into 1st. No engine fires every cylinder 100% of the time. You don't have to remove the base idle screw cap to adjust the base idle speed , it still could have been messed with. 88 Chevy 454 TBI Idle Adjustment. Most idiot lights (IIRC) come on at less than 10 psi of oil pressure. No point in checking the timing unless that is unplugged. Truck starts and runs fine at first. Self taught, barely backyard mech status, for the love of the game. 1992 Merc 454 7. Can i swap out to a 360 and use the same transmission or do i need to. When shifting into drive, engine runs at idle rpm, when throttle is pushed down to come off idle, engine coughs & dies. Re: 1990 GMC Tbi 454 help Post by user-612937456 » Wed Jun 01, 2016 2:19 pm For diagnostic purposes to eliminate the EST timing control try unplugging the EST module and back the distributor up to 6 degree's below specified timing. 3 out of 5 stars 26 $39.