OldAussie

I have a 1986 Trans Am 305 TPI that I bought as a non-runner 5 years ago and I have not tried to start it until now. I live in Western Australia where parts and information are difficult to find as these cars were never sold new here. The car has 75,000 miles on the odometer.
It is fitted with a re-manufactured 1227165 ECM with 0600ID calibration code and a AUM 01228291 Cal-Pac. I have fitted a new fuel pump and filter. New spark plugs and leads. All vacuum hoses have been replaced. All 9 injectors have been serviced and tested and they all perform to manufactures specifications. The Fuel Pressure Regulator holds vacuum when tested. The fuel pressure is 44psi when the key is turned on and this drops to 36psi when the engine starts. When the throttle is opened quickly the pressure rises to 40psi momentarily and then drops back to 36psi. When the engine is switched off the pressure rises to 40 psi and this pressure is held for at least 24 hours. When tested both the TPS and the Temperature Sensor meet manufacturer's specifications. There is only one cooling fan that is controlled by the ECM. This fan starts at 227 degrees Fahrenheit and stops at 209 degrees. All of the cylinders have at least 190psi when the compression is tested and they are all within 10psi of each other.
The cold start injector switch tests OK and unplugging it when the engine is warm makes no difference to how the engine runs.
The exhaust is fitted with a catalytic converter but no muffler. The TB was cleaned when it was removed to service injectors. The PCV valve has been replaced. A new IAC has also been fitted. I have fitted a MAF from a car that was running OK and both these sensors produce the same air flow data when using TunerPro.
I have been unable to find information about interpreting TunerPro raw data but I can see engine starts in open loop and enters closed loop at operating temperature. The Oxygen sensor is working and the mixture fluctuates between rich and lean. The IAC is working and the EGR valve works once engine is above idle. I can also see that the temperature sensor closely corresponds with the temperature gauge on the dash as does the Tachometer.
When the engine is started the throttle needs to be held at about 1500RPM for a short while otherwise the engine stalls. Usually after this it will idle but the idle speed seems to vary each time the car is started ranging between 900 and 1100RPM. Sometimes however it will not idle at all and the engine runs very rich producing black smoke. Even when it does idle the exhaust smells rich and there is a roughness to the way the engine runs.
I have bench tested the distributor and it meets manufactures specifications. The base ignition timing was reset to 6 degrees of advance and this increases to 20 degrees when the tan coloured wire is reconnected.
I have spent weeks now searching the net and working on the car but I cannot find the problem. I will certainly appreciate any help in solving this problem.
Tim

afremont

Wow, nice detail. I take it you have tunerpro showing you all the sensor values. The rich, black smoking sure sounds like a bad temp sensor or connection, but you should see it with tunerprort. A sticky/leaking EGR could account for you having to give it throttle to keep it idling.

My car has always idled with a little roughness when it's warm, even when brand spanking new. It has 25K miles now and I replaced the injectors a few years ago. They made no difference in the roughness at warm idle then or now.

OldAussie

Thank you afremont for your quick reply. Yes, faulty temp sensor was my first thought as well. Although I do not have a new sensor to try I have tried another S/H sensor. I have also tested the original one and the resistance values are correct between 60 and 212 degrees. As I mentioned in my post the temp values that the sensor provides in TunerPro are also similar to those that appear on the temperature gauge on the dash so it's not the temp sensor. The EGR provides readings in TunerPro but I have not been able to find any information as how to interpret the readings. All I can see is that there are no readings at idle. Only when the throttle is opened do readings start to appear. Are you aware of a site that provides this EGR information?

Tuned Performance

iTrader: (92)

http://www.gmtips.com/3rd-degree/dox/tips/ecm/prom.htm

Tuned Performance

iTrader: (92)

I would think the ect or leaking injectors or slight tear in the fuel pressure regulator (you could pull the vacuum and check for evidence of fuel)

OldAussie

Thank you Tunedperformanc. I appreciate suggestions from someone as experienced as yourself. As I said in my original post I have bench tested the injectors and they are all fine. I also vacuum tested the Fuel Pressure regulator and it holds vacuum. Also the fuel rail hols 40psi for longer than 24 hours so there cannot be a fuel leak. I have changed the ECT and both units give the same temperature readings in TunerProRT and resistance values are the same for both units and they are correct for temperatures between 60 and 212 degrees.
It is 1:00 am in the morning here in Perth now , however in the morning I will check the Cal-Pac to see if there is a new date on it indicating it has been changed.
Even though I described it as a Trans Am it was sold new as a Machiavelli Max and so there is a chance that Henderson Motors did not carry out this modification.
Thank you again for your advice.
Tim

Tuned Performance

iTrader: (92)

if the date code reveals it has not been changed you can go to a newer calibration I suggest 89's $6E and eliminate the ninth injector. If you get too that point and need help let me know. I know a few guys in australia that might be able too assist.

Lucid

iTrader: (4)

Since you are using Tunerpro, check the TPS voltage with the key ON engine off, throttle closed. Should be at .54volts.

Also, pull off the MAF boot and look at the throttle blades with a flashlight. Work the throttle with your right hand and look inside, especially on the back of the throttle blades and see if they are dirty and oily. Probably wont help with the roughness but may help you narrow down the idling problems.

Are you using fresh gas and how old is the inline fuel filter?

AvantiHall

You have excess fuel, per post, set 5 years, can you put a scan tool on it and check O2 cross counts and block learn #;s? The computer should be trying to remove fuel, if not; exhaust leak near O2, slow O2, check the voltage swing of the O2 sensor and speed, It must be fast and go below .100 volt and about .900 volt if it swings in the minus or above 1.00 volts that is a problem. (-.150 to .750 its bias) an over torqued or power steering fluid leak on the sensor causes problem. Connection problems with wiring, check powers and grounds, bad or weak grounds will cause voltage to feed back skewing data.

Exhaust back pressure will cause a rich mixture, the EGR valve causes Idle problems if on a little, I use a temperature gun to see if its on when cold idling, push it up using a radiator hose remover pick. engine should stumble or die. do a cylinder balance all even, sticky valves, re-check fuel pressure holding 24 hours, junk may have gotten in to the injectors.

Miss fire, wrong heat range of spark plugs? You posted the fan range, does it have a 190 degree thermostat, if it has a 160 or even 180 degree thermostat it's right at the border line of the emission equipment working back then.

Air inlet restriction will cause a rich condition? I found a pair of panty hose in the inlet of a customers car once. open the air cleaner lid it would rev up put it back on and it bogged, also, air cleaner box filled with dog food, from mice storing for the winter.

I have the old prom, ECM book at my shop I'll check on updates on prom, tunedperformanc is correct on the newer updated choice, GM was in a very high learning curve when that car was made. We were updating the proms every 3 to 6 months. They didn't even know how to start the car without that extra injector, I wired my 88 to a momentary switch so I could give it an extra shot of fuel on very cold mornings, the cold start sensor would cause restart problems if you drove a very short distance shut if off then tried to restart.

Be sure to solve the running problem now, before trying to start a new tune, you'll go nuts! Are We Having Fun Yet ???

Dave

OldAussie

Thank you Lucid for your suggestions. As I wrote in my first post I removed the throttle body completely when I serviced the injectors. Whilst it was off the car I changed the water jacket housing gasket and cleaned and polished the butterflies and the interior of the housing. And yes I removed the TPS to test it accurately and then I reset it with a voltmeter when I refitted it. TunerProRT confirmed that I had reset it correctly at 0.54 volts when throttle is in idle position.
I also explained that I had fitted a new fuel pump and filter. In doing this I emtied the fuel tank to remove it from the car. Whilst out I cleaned the inside of it thoroughly. Once reinstalled in the car I filled the tank with fresh fuel.

OldAussie

Thank you Dave for taking the time to answer my post and to impart to me your knowledge and experience. Unfortunately I was unable to fully understand your first sentence. What does “set 5 years” mean? I will have to check the data coming from the O2 sensor tomorrow but I do know that during the open loop phase the computer only responds to data from the TPS, the ECT sensor and the MAF sensor. The problem that the car has is occurring in both open and closed loop and is more noticeable whilst in open loop which would seem to discount the O2 sensor as the problem . As I mentioned in my post the exhaust system does not have a muffler at all and the catalytic converter is almost empty. I have also tried running the car with the catalytic converter removed and this makes no difference. The new spark plugs are the heat range recommended for the car and they are the same type as those that were fitted to the car when I purchased it.
The thermostat is 190 degrees and the car is fitted with only one fan which is controlled by the ECM. The only way I can change the cut in and out temps for the fan is to either reprogram the ECM or fit an aftermarket thermo fan switch. The car is not yet ready to drive on the road and I have been running the engine with the air cleaner removed after the MAF sensor. I have tried using another MAF sensor as well and so I am sure there is no blockage in the air intake. I had to remove the fuel tank to change the fuel pump and I had to drain it to do this. Whilst out of the car I thoroughly cleaned it inside and I also blew out the fuel lines before fitting a new filter and re-fitting the fuel rail.
I took the advice of tunedperformac and checked the Cal-Pac. There is no sticker with a revision number or any hand written date. The car was manufactured in October 1985 so it is one of the very earliest cars to be fitted with a 1227165 ECM. As I stated in my original post though, this ECM is not the original one because it is a re-manufactured one. How can I tell if this Cal-Pac is the original one or not? Did all the new ones that were sold and supplied later also have these revision stickers? Again thank you for your advice
Tim

OldAussie

Thank you again tunedperformac and I checked the Cal-Pac. There is no sticker with a revision number or any hand written date. The car was manufactured in October 1985 so it is one of the very earliest cars to be fitted with a 1227165 ECM. As I stated in my original post though, this ECM is not the original one because it is a re-manufactured one. How can I tell if this Cal-Pac is the original one or not? Did all the new ones that were sold and supplied subsequently also have these revision stickers? Again thank you for your advice
Tim

Tuned Performance

iTrader: (92)

I have never seen any other sticker other that the broadcast code on the AUM even for the updated calibration. Just the numbers on the Netress chip .

If the date code is not 8646 (1986, 46th week) or higher, your PROM has never been changed.

OldAussie

Thanks tunedperformanc but I'm still unclear how to interpret the numbers on the chip. This chip has a sticker with the numbers: 6243
1621
3684

The numbers on the chip itself are: 014
69300
89429AB
What does this mean?

Tuned Performance

iTrader: (92)

The 69300 is a 27c128 eprom. The number you need too look for is on the bottom of the small chip (netress) 16055376 this is the manufacture ac delco date code. you can see in the picture a AMU I have that is 8603 this was produced in 1986 on the 3rd week. There was no issues with this limp home chip but the errors with the calibration loaded into the eprom.

OldAussie

Thank you again tunedperformanc but my Cal-Pac is different as it has two of the blue CT89602 chips. One is 16055376BU and the other is 16055375BU

Tuned Performance

iTrader: (92)

If there is no date code not sure what too say

Lucid

iTrader: (4)

It almost sounds as if the car is running in limp home mode. Before looking at the sensors, do you have any trouble codes? When you start the car, the SES light should come on momentarily and then turn off.

I have had a third gen with a faulty ECM show some of the signs you speak off. Having to hold the throttle down to get it to start, but this was on a carb car. The SES light was flickering many times per second and the car ran absolutely terrible. I have also had an ignition module fail and had an extremely rough running TPI car with black smoke.

Having said that, do you have an audible leaks? Vacuum leaks or exhaust leaks? If you are leaking air into the exhaust anywhere near the O2 sensor, its going to run rich.

OldAussie

Thanks Lucid, the "service engine soon" light goes out when the engine first starts but comes back on again after a few seconds. It then stays on until engine is switched off. When A and B pins on the ALDL plug are shorted out only the 12 code is displayed. I have removed the distributor and this performs to manufacturers specifications on the bench, so its not the module or coil.
With this ECM/Cal-Pac when the engine first starts and it is in open loop the ECM does not respond to the signal from the O2 sensor and yet this is when the engine is running at its worst. So it would appear that the problem is not the O2 sensor. There are no audible vacuum or exhaust leaks and I have replaced all of the vacuum hoses with new hose.

Lucid

iTrader: (4)

Do you have another '165 ECM to try out? You say that the ECM was remanufactured but did it come with the car or did you purchase the ECM when you were trying to get it running?

I had a '165 ECM on my TPI go out and some of the symptoms are starting to sound familiar but replacing the ECM was the absolute last thing I did. I think what triggered me to replace it was lack of code output when the SES light was being illuminated. If you have a buddy with a TPI engine from 1986-1989 you could "borrow" their ECM.

Tuned Performance

iTrader: (92)

or even the australia 1227808 ecm should do the trick with your memcal

AvantiHall

AUM3236 prom part no. 1228291, release date 9/86, ecm 1227165 update no, final. was to correct driveability/ false codes 32, 34, 43, 44. 1986. 5.0. V-8. Pontiac. Vin. F. Scan tool ID 8291

Hope this helps
Dave