My car has trouble idling to the point where it is impossible to keep the car idling until the engine warms up then it's just about ok. The scanner information was taken after the car had been warmed up as it is impossible to idle it cold without keeping your foot on the gas a little.

Car has new cap, rotor, wires and a coil is on the way from Summit.

I can only think that it can be 1 of a few things, or maybe all of these tinhgs?

1. The place that rebuilt my engine has the timing advanced far too much. I'm waiting for my timing light to come through with my summit order and then I'll fix that.

2. The TPS wasn't reset properly.

3. the IAC isn't working properly.

I went out with my auto scanner and got the following:

PROM ID 102

coolant temp: 232.7*F
TPS: 0.68 Volts
Engine RPM: 1010 RPM
O2 Sensor 544 mVolts
O2 Cross counts: 221
IAC: 43 steps
Desired Idle: 862 RPM
Engine load: 44
Manifold Air Tem: 136.4*F
Spark advance 29*
Knock sensor: 13
Knock retard: 0*
Injector pulse 1.9ms
MAF: 9gr/sec
Open loop

Anyone got any ideas as to what the problem could be? I've got more scanner info available and will type it if it needed. I now see the benefits of PC link-up.

Help is appreciated.

Robert

 

If you don't have a timing light, how did you set the static advance when you installed the distributor? If the rebuild place did it, you have some amount of warranty coverage...

Looking at the ALDL snapshot it looks like your coolant temp is awfully high...232degF ?

Your TPS voltage, assuming your foot wasn't on the gas pedal, is high. Set it as described in the tech article, should be 0.54VDC +/- 0.01 or such. Definitely less than the 0.68V you got.

I'd do the following, in the sequence listed:

1.) set the TPS voltage,
2.) check and adjust the initial spark advance w/ a timing light,
3.) then run thru the IAC reset procedure,
4.) then re-check and re-adjust TPS voltage if needed.

Let us know how it goes.

-Kevin

 

Kevin,

Thanks for the response. With regards to the timing, I've taken it bak to the place that did the work and they argued the toss with me. I keep this car over in the UK which is where the work was done. After everything was finished I realised the timing was far too advanced. I told them that it had to be set to 6* and they told me that was rubbish and that the computer would just advance it anyway. No matter what was said they would refuse to accept that I was correct even when I told them that the computer "assumes" that the base timing is 6* as it cannot read the timing itself.

With regards to the cooling temp, the fans came on moments after the reading was taken. Both fans are wired to come on at the same time. I'm thinking that they both come on at the higher temp (225*F?) , rather than the lower one.

I'll alter the TPS tomorrow and see how that goes. I'll keep you posted. Thanks again.


Robert

 

RMK,

Kevin has you pointed in the right direction. Setting the TPS correctly may help some of the IAC issues, maybe not. If you're still having problems with it after everything else is set correctly, you may need to remove, disassemble, clean,lube, and reinstall the IAC to restore is operation. (Incidentally, the IAC counts seem a bit high.)

Definitely start at 6° BTC base timing. If you're arguing with the shop, remind them that YOU are the customer. There is a very good reason that the factory specifies that base timing. You might also remind them that your car is not a Ford, and that it DOES matter. If you need to point out the EST bypass connector to them, don't be afraid to do so.

 

You're right, the shop is wrong. From my own experience, initial timing has a big impact on idle and driving behavior...even when the PROM is burned to accurately reflect the setting. My car hates anything above 10deg BTDC, nearly stalls when coming to a stop. Cranking is a bear also, I'm running 10.7:1 compression.

The ECM does it's spark management calculations from a constant value, which must accurately reflect whatever the distributor is set to with the ESC connector Vader posted disconnected. Any disparity between PROM and reality will cause problems.

I'd have one more go at the shop, promising to leave them alone on the issue if they'll just set it to factory specs. Shutting you up should provide enough motivation.

 

Yeah, I noticed the high IAC, but it was idling ~1100 rpm versus desired ~825...seemed like the ECM wasn't even trying to manage the idle. I figgered maybe the high TPS voltage had the ECM out of idle management mode?

Either way, the TPS then IAC then TPS again procedure will put him close to home.

 

Or you could show the shop the factory sticker on the underside of your hood. Has the timing specs right on there. If they dont believe that, then go to another shop.

 

Orig by RMK "I've taken it bak to the place that did the work and they argued the toss with me. I keep this car over in the UK which is where the work was done. ...... they told me that was rubbish and that the computer would just advance it anyway. No matter what was said they would refuse to accept that I was ....."


RMK has had a lot of hassle from the place that did the work for him. They really are pretty unapproachable and insist that they know best.

Even when RMK went in with the facts printed out they still refused to accept it.

KevinC and Vaders suggestions seem the best place to start.

How long has the problem been ongoing for. Does it only occur on really cold frosty mornings or all the time?