CEL and no error codes

[eoseitz]

I've been having an ongoing issue with my car stuttering when I come to a stop. The RPM move up and down. Probably between 750 and 850. Sometimes the car will stall too. I've been datalogging and my TPS appears to be around 11.3% at idle. I'm using MMCD so this sounds close. I think it should be at 10%.

When checking the ISC at idle its anywhere between 12%-40%. What should the ISC be at during idle? I've also noticed my FTRL is at 139.8%. This seems really high for my low fuel trim isn't it? Could my car be leaning out at idle?

I know I removed the combs from my maf a long time ago. Could this be throwing air flow settings off? How can I correct this?

Please help? I'm so lost on what to check.

 

[stevo911]

I beleive Rush had an issue with removing is combs from the MAF throwing off airflow. Do you have another MAF you can swap?

 

[rush2252]

yes I did have issues. At idle it showed X amount of increase w the combs removed. The car was running pig rich due to this. It also affected boost levels idel etc. I would say that is your only problem but I know it made my 2g run worse. Fuel trim should be <100 high low and mid. The ISC is going to fluctuate constantly. Try checking for boost leaks. It could be small enough that your not noticing it while under boost but more at Idle. I know the EGRs on the 2gs are a bi*** for leaking

 

[eoseitz]

Unfortunately I don't have another MAF. I may still have the combs though. I don't know if they'll fit back in correctly or not. I also have the EGR block off plate. I just haven't put it on yet. How hard is it to install? I really want to take off all the emissions stuff, but I'm half afraid I'll disconnect the wrong vacuum line and not know which one is messing things up.

It def sounds like your problem though. How'd you fix yours? A new MAF or did you upgade to a GM?

 

[illeffekt vr-4]

To properly set the TPS follow this link TPS Adjustment

To check/test the ISC follow this link DmTaLoN's Idle Speed Control Test/Fix Page!


I don't know what the values should be on your logger but I know that with dsmlink you want the TPS to show between .45 volts and .55 volts for a 1g and .63 volts for a 2g.

And the ISC should be at 30-32 at idle. So the BISS screw should be set so that the ISC shows 30-32 and the ECU should take over from there.

 

[eoseitz]

Does anyone know if these values are the same with the MMCD datalogger. These values seem really far off from what I'm seeing.

So its really strange. My check engine light has started coming on when I'm cruising. Usually around 55 MPH at around 2500 RPM. The thing will come on and go off as I drive. I've tried to catch an error code with my datalogger, but it says there are none, even when the CEL is on!!!
What could be causing this?

 

[95gskid]

i took the lower combs outta my 2g maf, and had the same issue... the only way to correct the idle problem is to use a AFC or put in a new MAF. When you take out those lower combs it fools the computer into thinking that there is more air coming threw the maf then there really is so it compensates with more fuel, hence the crappy idle *sounds like you have a huge cam* Since you have a 1g swap it out for a STOCK 2g maf since its an upgrade anyways or put a new 1g maf in should fix your problem

 

[eoseitz]

I've actually never changed the cam in the car. I don't know if the prior owner ever did. I kind of doubt it. The car was in shambles when I bought it. I've literally rebuilt the whole thing. Entire break system, top half of engine, some of the intake system and a lot of cosmetic work. Looks pretty good now and runs real well. If I could fix this darn idle problem.

 

[95gskid]

no no no, i mean't it would sound almost like it was cammed ### of the bad MAF sorry. but if you search you can find out how to switch over to a regular 2g maf

 

[Auto RS T]

So its really strange. My check engine light has started coming on when I'm cruising. Usually around 55 MPH at around 2500 RPM. The thing will come on and go off as I drive. I've tried to catch an error code with my datalogger, but it says there are none, even when the CEL is on!!!
What could be causing this?

Try pulling the code the old fashioned way and see what you come up with using an analog voltmeter and probing the data link connector under the dash.

http://www.dsmtuners.com/forums/articles-tuning-ecu/319844-1g-code-reader-cel-code-reader.html

Have you checked for a simple vacuum leak? Have your FTRL always been 139% since the hacked maf, or only since this idle issue occured?

 

[eoseitz]

Well I can't really use a volt meter to check the error code. The only time it comes on is when I running at cruising speeds. I've notice it only comes on between 55-75 mph. It goes of at all other speed ranges.

I took the combs out quite a while ago. Even before I had a datalogger. So I really have no way of knowing my fuel trims before I did it. I know the car ran fine for a while after I did it. So who knows if that's what's really causing it. The CEL just started coming on since I put in an eprom ecu. The idle problem has been ongoing though.

After reading the info from the last link posted about ECUs I see that an error 43 and 44 is a common thing if you replace capacitors in your ecu. I'm pretty positive they are different caps. They have a far higher temperature rating than stock ones. Is there a way to correct this, or do I have to live with it?

Are 2g ecu's plug and play with the 1g if I get the conversion wire? I might just get one of those to see if it fixes the problem. I see those at the junk yards all the time.