Can anyone tell me exactly what sensors and such the car uses once it reaches operating temperature that it doesn't use when it's cold besides the O2 sensors? I'm trying to figure out why my car runs good cold and like crap once it's warmed up and why I'm not getting an SES light. I have a '96 but it has the OBD1 conversion if that makes a difference. Also, closed loop is when it's cold and open is when it's warmed up, right? or do I have that backwards? thanks

Myles

 

There's no difference in the sensors used, other than the O2 sensors.

You have it backwards. It STARTS in open loop. The "open" loop is the feedback loop from the O2 sensors to the PCM. No feedback, since the sensors don't work when they are cold. Additionally, the target A/F ratio at cold start is not 14.7:1.... its enriched for cold start. The long term fuel corrections are used for the injector pulse width calculation, but the short terms are locked at 128, since they are determined by the O2 sensor feedback, which isn't being used.

After the O2 sensors start to work, the coolant reaches 120-140*F and the timer times out (~200 seconds), the PCM "closes" the loop by accepting feedback from the O2 sensors, and using that feedback to adjust the short term fuel corrections and eventually, the long term fuel corrections.

If you have a problem when it warms up, it could be that the O2 sensors are providing faulty data, and when the short terms are activated in closed loop, they provide "too much" correction (long term correction is limited to +25%, -15%), based on the faulty O2 sensor feedback. Or, maybe its running lean in closed loop, but runs better with the richer A/F cold start ratios.

Have you scanned it for codes? Do you have data logging software that would allow you to access the long term fuel corrections, and other sensor and PCM data and parameters?

 

I don't have any data logging software and my scanner is an Autoxray EZ-Read 2000 and it can only scan and when I used it I didn't get any codes. The thing I don't get is my car ran beautiful last summer then one day just wouldn't start, turned out to be the opti that only had 16,000 Miles on it. I didn't want to be changing opti's every 15,000 miles so I went with the Delteq system over this spring and bought the Dynaspark Gen 3 opti which is just the optical sensor for the Delteq and LTCC systems. That's all that I changed and now the car is doing this crap. Normally I would say whatever I changed would be the culprit but I don't see how anything in the ignition system would work fine in open loop then all of the sudden run like crap in closed, doesn't make sense to me unless I'm missing something. I thought maybe the ignition module was getting heat sink but I mounted it on top of my intake which is a lot cooler than mounting it on the valve cover like they orignally intended. At first I thought it was the 02's so I took them out and unplugged them and drove the car and it still acted the same, the only difference was the SES light came on. Do you think it could be a programming issue? I dunno if this helps any but my buddy and I put a timing light on the plug wires just to see how they were firing after it warmed up and every cylinder would skip intemittently, no real set pattern, just here and there. Could my MAP be bad but just not throw a code? sorry for all the ?'s, I'm just lost on what it could be. Oh yeah, the car doesn't backfire when cold, but does when it's warmed up so it is running rich in closed loop, and it never backfired last summer either.

 

I've seen a few people install the Delteq and have all kinds of problems. After consulting with Delteq (when Delteq still existed) and trying numerous suggested "fixes", they were told by Delteq "the system just doesn't work on some cars", and to send it back for a full refund.

Just a thought.

 

I thought about that too but I would think it wouldn't work at all or run like crap all the time, not just after it get's warm. I dunno, the search continues I guess.

 

Is the Delteq module located somewhere that it heat soaks as the engine warms up?

 

Then it is not an open-loop closed-loop problem. It is a cold-engine warm-engine problem.



That certainly points to the delteq/dynaspark, which as you noted originally, is the obvious place to look since it is what changed.

 

if what you mean by module you're referring to the Opti-box it's located on my supercharger bracket about 3-4" from the head, if you're talking about the ignition module it's on top of the intake.