anyone have this issue? it only does this at a steady rpm if I change rpm a few hundred or so it goes away for a few seconds and will start at that rpm. unless I have the rpms real high like 3000 rpm. if I don't change or raise rpm it seems to get worse. IAC does not seem to be related with this surging and I belive the surging is faster than the IAC could ever move anyway but, timing changes as you would expect and is hard to see if this is causing it or not?

I guess I am not really too sure what to look for. maybe there is a table for slowing down the timming changes at cruise? or perhaps I need to make a whole new timing table that is a lot more flat?

see sig. 6e - manual trans

 

Have you checked to see what MAP this is happening at? I get a bit of a surge right around 1700-2000 rpm with high manifold vacuum, ie 25-30kPa in trailing throttle situations especially on slight decline.

 

Sounds like too much timing, or not enough fuel.
That's also right in the range where reversion can set in, and with a MAF system can play havic with the tune.
What are your BL's when this is happening?.

 

my block learn is not really working.

it stays in open loop unless I add fuel. then the o2 will start reading very low which starts closed loop and then causes the bl to max out adding fuel.

well anyway since a heated and none heated o2 is worthless. So I read my plugs and the best I can tell by reading my plugs is I am on the rich side already with out adding any extra fuel.

 

I think Bruce hit the nail on the head "Too much timing or not enough fuel". Have you accidentally enabled Highway Mode as this is one of the symptoms if you have too much timing or too lean a mixture.

Another major cause of surging is the EGR. Try disabling it and see if the problem goes away. I am not that familar with the 1988 32B Maf Calibration, on some of the calibrations when the EGR is working, the ECM will add a couple of degrees to the spark.

 

It is 6e mask well, I am running the arap bin (stock spark map) but I have the hsr so there is no egr. maybe I should pull some timing from the lower load tables?

the car runs very well with a few minor issues like this and how it is cold blooded to work out. I wonder if I can't dummy the settings in the chip to be more basic like a carbed non ccc would be?

 

You might take a really close look for some mechanical problem causing your issues, vacuum leak, fuel pressure, etc., etc..

 

I will check again, I already checked for vacume leaks befor but with maf I would think a vac leak would cause it to run lean not rich.

I checked fuel psi and it checks out fine but, I can't drive with the guage on because holley has some retarded shrader valve that leaks with every adapter I use with my guage.


I have the vac guage on and I get less than 10 inches of vac at idle. but from what I have seen this is normal with a cam like mine

 

I don't know how you "disabled" the EGR in your calibration, but it wouldn't be the first time that I found someone didn't disable the EGR properly in the calibration. Turning off the diagnostics (for the EGR) doesn't disable it. I prefer to disable it by making the "temperature" to enable the EGR 255.

 

i had some real bad surging.. pretty scary cause the car would just lunge forward when i was stopped at a red light or something so i had to keep my distance.. but my problem turned out to be the coolant temp. sensor.. after i changed that.. it stopped

 

so even though there is no egr I need to do that?
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I have spares so I guess I can just swap them out

 

YES!!!

 

ok, there is no egr vs coolant in the tunercat tdf I am using. there are tps enable and disable scales (I think I could set them very high or very low?) or I could add the coolant enable table but, I don't really understand how I should be entering in the addresses per the tunercat tdf editor.

 

Try using TunerPro. The .ecu and .xdf are more complete.

 

If he doesnt have th EGR temp turn on/off in tunercat his files must be 3+ years old or more.

They are there, I have them for SD and MAF setups.

later
Jeremy

 

yes, very old. I used them back when I had my 88 and it still was n/a



on another note I noticed my pcv elbow was kinda loose so I went to the store and picked up a chrome one in hopes that it will stay tight being made of metal vs plastic. and I removed the plenium and made new gaskets since the holley ones never fit very well. I drove it and it seems better but, I still have the same problem which looks like I will have to see what tuner cat says for my tdf. I will let you guys know how it goes

 

I have the same problem with my 88 iroc and HSR. Did you hook up a scanner yet to read what its doing, my problem is in the RPM's that the ECM thinks it is. Meaning At an idle with my tach reading 1000 rpms the scanner is telling me the ecm thinks iam running 2500-3000 rpms, with my tach sitting on 2000 the ecm is reading 5800. But it surges bad from 1500-2500 and is very hard to pull out with b/c it causes the car to jerk hard letting out the clutch. I would check to see if your ecm is reading the right rpms as well, i just wish i could figure out what is causing mine to more them double my actual rpms.

 

my tach is just like the one in my 88. they must be freeks because they both are dead on the money even at red line.