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Old 04-25-2009, 02:29 AM   #1
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Car won't idle or stay running please help

Hey I'm new here and this is the rundown.

My dad's 88 GTA sat for 10 years and now I've been putting time and money into it. Car blew a headgasket when I was 10 years old and now I'm 20 and and mechanically inclined and ready to get it running.

When my dad put the heads back on he didn't set the rocker arms correct, which made it run poorly, and in 10 years of course it needed a full tune-up, new fuel pump, I drained the gas tank and added fresh gas and, and possibly other things that I need help with. According to my dad the car ran perfect before the thermostat clogged and blew the headgasket. Currently has 89k miles. I have the car started but it won't stay running and idk why, I set the rocker arms correctly with zero lash, and now the pushrods are pushing oil which before they weren't, fuel pump relay is bad so I just hot wired a switch to the cab for now. I turn the key and have to give it gas to hold it running but it will die if I try to let it idle, and the throttle response is rough. What am I looking at? Just old motor that needs to "wake" up after sitting for 10 years? MAF Sensor? etc.. Car is a 5.7 TPI by the way, please help and thanks.

Last edited by f1aws; 04-25-2009 at 02:58 AM.
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Old 04-25-2009, 03:02 AM   #2
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Car: 88' IROCZ
Engine: 388 TPI Motown 350 Race block
Transmission: 700R4
Axle/Gears: 2.77

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Re: Car won't idle or stay running please help

Probably something you don't want to hear, top end sounds like it needs a refresh. Cam, pushrods, and lifters high possibility of damage from lash too tight, and no oiling.
If it's not your daily driver (sounds like it's not) and you have a nice garage I'd tear into the top refreshing the heads, new gaskets, and check the cam & lifters. If you have to pull the cam put in a new set of gears & chain.
Having the intake system including the Throttle body cleaned up will help the idle especially if you have to set the minimum air rate (TPI.)
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Old 04-25-2009, 03:11 AM   #3
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Re: Car won't idle or stay running please help

The lash wasn't tight at all, the engine was running funny and I thought it was a firing order/timing issue but after checking that 4 times I pulled the valve cover off and 2 rocker arms were sticking. I pulled the arms off and bought new pushrods and a friend gave me these brand new roller tip rockers that he had in the corner of his garage. When my dad set the rocker arms, he just torqued them all at 45 and didn't set the lash so they looked like chattering teeth so they weren't overtightened. All the lifters are now pushing oil to the top end and the lash is set correct on every rocker arm. I don't have any sticky lifters and the bottom end seems to be working fine, crank turns, pistons go up and down, oil pump is pumping....

I do need to buy some carb/throttle body cleaner and spray some their. What do you mean by if I have to set the minimum air rate?
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Old 04-25-2009, 10:24 AM   #4
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Re: Car won't idle or stay running please help

Throttle Minimum Air Position

Tools needed:
1. Torx driver # T-20
2. Paper Clip
3. Small Punch
4. Tachometer

GENERAL NOTE: The engine should be at normal operating temperature before performing any adjustments. Never rely on the dash mounted instruments for diagnostics and adjustments. The oil pressure and temperature gauges and the voltmeter and tachometer just aren't calibrated accurately enough for diagnosis, but are a relative indication for monitoring the vehicle while driving.

For this adjustment, the transmission will be in DRIVE while you're under the hood. You will need to securely set the parking brake and block the drive wheels. It would also be a good idea to have an assistant hold the service brakes while you perform the adjustments.

In order to successfully complete the adjustment, the IAC air passages and pintle need to be clean. The throttle plates and bores need to be clean as well. If this is not the case, you'll need to remove the air cleaner from TBI engines or the intake air bellows from TPI engines to gain access to the area to be cleaned. A spray-type carburetor cleaner works well for this. Cleaning the IAC passages on a TPI/MAF engine will set a DTC, but we'll be clearing that later. With the engine idling, direct the spray cleaner into the IAC air passages and around the throttle plates. Shut off the engine and continue cleaning the throttle plates by opening the throttle manually. Once everything is satisfactorily cleaned, replace the air bellows on TPI engines. Many times, this alone can solve IAC/idle speed problems.

If this doesn't solve the problem, you may need to remove and clean the IAC stepper motor. If the IAC appears to be clean and functioning properly, continue with the adjustment procedure.

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Idle Air Control Cleaning

You can remove the IAC and service it. Remove the electrical connector from the IAC. Unscrew the IAC unit from the throttle body.

You can gently rock the pintle back and forth and allow the spring to extend it until it comes apart in your hands. Clean everything with lint-free cloths and a mild solvent. Harsh solvents can affect the insulation of the stepper motor coils. It's generally the dirt and buildup on this worm shaft that causes sluggish IAC operation.


Click the image to open in full size.


When the worm gear on the pintle shaft is clean and dry, apply one drop of clean light oil to the shaft. Measure the free length of the spring, adn stretch it carefully if necessary to make the free length at least 2". Assemble the parts in proper order, start the pintle shaft into the stepper motor in the correct orientation (paying attention to the keyways), and work the pintle back into the rack gears of the motor by the same rocking motion. It takes a while to get the pintle back into the worm gears, but you'll get it. It is important to get the pintle fully retracted into the housing so that the pintle is not forced against the gears when reinstalling the IAC unit in the throttle body.

While the IAC is out, clean the air passages in the throttle body. The oriface in the TB where the IAC resides is the seat that the IAC valve closes against, and it can accumulate a lot of carbon, dirt, and debris. The easy way to do this is with carburetor cleaner and a small stiff brush.

When everything is clean and dry, replace the gasket if it is damaged, apply a little anti-seize to the threads, and torque the IAC to the proper specs. (13 ft/lb for '85-'89 , 30 in/lb for 1990-on.) Proceed with setting the TPS and minimum air position.

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Locate the Assembly Line Diagnostic Link connector under your dash panel. Remove the cover if it is still there.

Click the image to open in full size.


Cut and form a paper clip into a "U" shape. Insert the clip ends into the ALDL in the 'A' and 'B' sockets.

Click the image to open in full size.


Turn on the ignition, but DON'T start the engine. This will force the ECM into its diagnostic mode. Wait 30 seconds to allow the IAC pintle to fully extend. With the ignition still on, go under the hood, remove the electrical connector from the IAC, then turn off the ignition and remove the paper clip jumper from the ALDL. With the IAC pintle fully extended (closed) all idle air will be controlled by the position of the throttle plates. Some manuals indicate that the EST bypass connector should be disconnected for this procedure, while some make no mention of it. While timing is a factor in idle speed, the EST should only operate as a function of engine RPM, temperature, and detonation sensor inputs. To remove all doubt, disconnect the EST bypass connector is your car is so equipped. Some TBI and V-6 engines do not have this bypass connector, and therefore must be set with no regard to the EST system. The EST can be bypassed on some cars by grounding the diagnostic terminal at the ALDL and continuing with the procedure, but the fuel mixture will be skewed to the rich side, affecting idle speed as well. In any event, the minimum air position idle speed range is wide enough to allow for some variations. As always, it is best to consult your service manual for the exact procedure for your system.

Locate the Torx screw on the left side of the throttle body. It may be equipped with a protective metal cap from the factory. This was intended to discourage adjustment. If the cap is present, use a small punch to knock it out. Once the screw is accessible, start the engine and place the transmission in DRIVE. Adjust the throttle stop to obtain 400-450 RPM with the transmission in "DRIVE" on an automatic transmission car, 450-550 in neutral on a manual transmission car, rotating the Torx screw clockwise to raise speed and counter-clockwise to lower speed. Once the idle RPM is set, place the transmission in PARK and turn off the engine.

Re-connect the electrical connector onto the IAC. Start engine. Idle speed should be governed by the ECM at approximately 600-650 rpm in "DRIVE" (for unmodified cars). Idle speed in NEUTRAL or PARK is less significant, and will be higher.

Click the image to open in full size.

Throttle Position Sensor (TPS)

Tools needed:
1. Digital Volt-Ohm-Meter (VOM)
2. Breakout jumper wires or probes (make your own)
3. AutoXray, Diacom, or similar scanner will replace the VOM and jumper wires.

Turn on ignition, but don't start the engine.

With a diagnostic scanner: plug in the scanner and read the TPS voltage. It should be 0.54Volts +/- 0.07 VDC.

Connect the VOM to the TPS electrical connector terminals A' and B'.

With a breakout jumper: Disconnect the electrical connector from the TPS. Install the breakout in-line, between the TPS and wiring harness connector. Connect the meter probes to terminals 'A' and 'B' on the connector. (B' is the positive connection, A' the signal ground, or negative.)

With probes: If you have very slender probes on your VOM, you can back-probe the TPS connector while it is attached to the TPS. If you have made probes of large dressmakers pins or a similar item, you can back-probe the connector as well. Connect the meter probes to terminals 'A' and 'B' on the connector.

Turn on the ignition to read the TPS output voltage at the idle position. The reading should be 0.54VDC +/- 0.07VDC. The ideal is the center of the range, 0.54VDC for a stock engine. To adjust the output voltage, loosen the two Torx screws holding the TPS to the throttle body, and slightly rotate the TPS up or down, reading the voltage until it comes into specification. Tighten screws. Using the throttle lever, rotate the throttle to WOT (wide open throttle). The TPS voltage should be over 4.0 volts. Close the throttle again, and then slowly open it to WOT, observing the voltage reading. It should increase progressively and in a linear fashion. If it sticks or jumps or falls off at all while doing this check, the TPS sensor may be failing and could be a cause of stumbling and driveability problems.

After achieving the desired setting, turn off the ignition switch. Remove all jumpers or the scanner and reconnect the TPS connector as required.


Reinitializing the ECM

If you set a DTC during the procedure, the SES light should be illuminated on the dash. This ECM retains DTC data for the previous 50 engine starts, so the codes will eventually be cleared. If you want more immediate results, after shutting down the engine disconnect the negative battery terminal for five minutes. This will clear the ECM of all diagnostic trouble codes. Clearing the ECM also clears any data learned about your engine, and clears the radio presets. If you have a Delco-Loc or Theft Loc II radio, make sure you follow the procedure to unlock the radio protection before disconnecting the battery. This five minutes is also just about long enough to clean both battery cables. Reconnect the battery. When you first start the engine after clearing the ECM, the engine will operate with base parameters programmed into the ECM PROM. These parameters may not be optimum for your engine, but the ECM will enter a Block Learn Mode soon after the engine is warm and enters Closed Loop Mode. The ECM will write new data tables specific to your engine and will eventually rely on those tables instead of the base tables of the factory program. You can expedite this process by driving the car for 20 minutes under varying conditions to allow the ECM to initialize. Or you can wait and drive the car normally at your convenience. The BLM tables are constantly being updated as sensor input ranges change, but the greatest change will occur within the first twenty minutes of Closed Loop operation.
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Old 04-28-2009, 06:51 PM   #5
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Re: Car won't idle or stay running please help

Here's a update.. I use a jumper on the ALDL connecter to go into diagnostic mode and it threw codes 36 and 51, MAF Sensor Burn-Off Circuit and PROM? Can someone elaborate exactly what needs to be replaced?
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Old 04-29-2009, 08:49 AM   #6
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Re: Car won't idle or stay running please help

Anyone??

How do I fix codes 36 and 51 exactly? New prom? New maf relay? New ecm? Is a bad maf burnoff throwing a prom code?
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Old 04-29-2009, 08:14 PM   #7
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Re: Car won't idle or stay running please help

I replaced the 3 relays in the corner of the engine compartment next to the brake booster, car seemed to run a LITTLE better, but still choking, seems electrical.

Throttle response is good at some points, and an hour or two later it will run choppy. Sometimes when I start the car it will run for like 5 seconds and then turn off, I'm starting to think it's an electrical problem, and when I shut the car off the red light on the dash next to the steering wheel blinks fast and I can't lock my door, like there's an error or something.. anyone have any ideas on what to try?
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Old 04-29-2009, 08:14 PM
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