1987 Park Ave 3.8 V6 FI Trouble starting & Check engine

[doug2060]

Before I waste any money on this old car I wanted to get more info. My 1987 Park Avenue 3.8 V6 fuel injected with 160,000 just started acting up suddenly. I could not get it to start at all. It wouldn't even act like it wanted to start. I then pushed the gas pedal all the way down fully opening the throttle then tried and it started but was somewhat hesitant. The check engine light comes on shortly after starting the car, but the car seems to run fine after that, other than a possible slightly higher than normal idle which may not be related. It will crank everytime this way ONLY. Any help is much appreciated.

[wrightz28]

Check the fuel pressure regulator vacuum line to see if it's been knocked off or has gas in it.

Other than that I'd pull and clean the IAC off the throttle body, my 87 would get crudded up fairly often.

And, retreaving the trouble code would be a good thing to help.

[Blue Bowtie]

Welcome Aboard!

Only 160,000? That's barely broken in. 300,000 on the one-gallon Buick engine is not unheard of. That's why everyone has tried to duplicate the engine, from Ford to Toyota.

Read the error codes stored in the ECM memory. That may offer a clue as to why it is not starting reliably.

You’ll need to acquire a GM ECM Diagnostic Trouble Code Retrieval Tool. (Most of us just call them “paper clips, but GM has to have some fancy name for them to charge more.) Cut the clip in half so that one end of it is still bent in a “U” shape. If you’re careful, you can make TWO “error code retrieval tools” from one paper clip.

With the engine and ignition turned off, locate the ALDL connector under the dash, just to the right of the steering wheel in the driver's foot well area on some models, and on the left on others, depending on the make and year. There may be a small rectangular cover over the access hole in the lower dash trim.



Insert a jumper tool or the aforementioned paper clip into the 'A' and 'B' terminals on the ALDL connector:



WITHOUT STARTING the engine, turn the ignition to the "RUN" position. Watch the Malfunction Indicator Lamp (MIL) - it will begin to flash. This is also commonly called the “Check Engine”, “CEL”, "Service Engine Soon" or "SES" lamp. The first code will flash three times, and will usually be a code '12'. This is encoded by one flash of the lamp, a brief pause, then two successive flashes of the lamp. Each code will repeat three times, so you should see a "Code 12" flash three times. Any other error codes will follow in numerical order, and each code should flash three times. After all codes have been displayed three times, the "Code 12" will again flash three times, then all other codes will follow as described earlier. This cycle will continue until the jumper is removed or the ignition is turned off.

After you have made a note of all error codes, turn off the ignition and remove the jumper immediately. If you forget to remove the jumper and attempt to start the engine with it in place, you could damage the ECM. For this reason you should remove it immediately.

Once you have a note of all error codes, check this file for the decoding:

GM Error Codes.pdf.

[doug2060]

Thats cool, I will try it later today and reply. I didn't know that. I thought I would have drive 1hr to borrow my dads obd tool to get the codes. Thanks alot.

[wrightz28]

Your connector is in the center of the dash straight over the exhaust hump.

[doug2060]

OK, I got error code 21 which is TPS (throttle position sensor) voltage high. Would this cause my issue? Do I replace the TPS or is something causing it to get higher than acceptable voltage? I am sensor illiterate! I hate sensors!!!

[wrightz28]

That'll do it.

There are 2 screws that hold the TPS in place, perharps they came loose The TPS has eliptical mounting holes to adjust the 'base' voltage which should be about .48V at idle.

[doug2060]

Would it possibly just need adjusting or should I replace it?

[wrightz28]

I'd try adjusting it first. However they are on the relatively chepa side, about $35 I think I paid. You do need a voltmeter (or scanner) to set it at .48V.

[doug2060]

OK, I tried adjusting and it must be bad. It did push it all the way to the right and it starts fine but the check engine light is still on. I will replace it when I get a chance. Thanks for you help.

[Blue Bowtie]

You'll still need a voltmeter to set the new TPS when you install it.

[doug2060]

Yes I know. Is there a special way I need to measure it. When I did it, I measured the voltage by testing the first wire as + and the last one-. It showed just over 5 volts no matter where it was positioned but fluctuated by 1 volt or so.

[wrightz28]

Yeah 5 volts is the full reference voltage.

Although it does sound as if you probed the correct wires from waht I remember

Just don't use the black (ground). And the harness must be connected.

With the engine off, backprobe the 2 wires, witht the throttle blade closed, set to .48V and it shoul dsweep to 4.5V at wide open.

[doug2060]

Thank you wrightz28 and Blue Bowtie for all your help. If it wasn't for you guys I would have paid alot of money I really don't have to get this car fixed. I really appreciate your help. I replaced the TPS and got it set to .48 at idle and it runs and starts perfectly every time.

[wrightz28]

Cool beans!