after day at track - surging much worse

[hcoles]

I briefly looked over the threads using search...
I had minor surging at just off idle....could be managed pretty easy.
Now after day at track with two drivers the surging is very strong even when putting the throttle down well past where the surging usually stopped.

The car seems to run fine otherwise, the idle speed seems constant. The exhaust sound does seem a bit louder... I'm running a stock exhaust with test pipe.

O2 sensor? Intake leak? CHT? engine moving around?

The O2 has been in there since day one, now I have 90k miles. CHT replaced at 46k. Top end done at 70k.

89 3.2

[Tooth911]

Best place to start would be to get sniffer exam and see fuel mix at the surge point. Vacum leaks or fuel mix or O2 sencer could be it.

[mca]

What happens when you disconnect 02 sensor? Any changes?

BTW ... is surging the same as "trailor hitching"?

[PatrickB]

injectors...

[hcoles]

I may have time tomorrow to disconnect the O2 and take a ride to see if there is a change.
A transmission mechanic I know describes trailer hitching... "when you come to a stop there is a sort of clunking sound as if the transmission slipped or made some sort of shift as the vehicle "rocks" back and forth after braking." something like that

the injectors should be good - WitchHunter about 2 years ago and just ran a bottle of Techron through... car ran great at the track, wasn't even back firing sometimes on shifts come to think of it...

[BReyes]

Hasn't there been a couple of threads on this issue couple years ago. I may recall reading a thread when was searching idle surge issue which was my microsensor was a little dirty. One thing I haven't done to mine is MAF. Don't they say MAF can get dirty inside? How do we know MAF is good?

[mca]

Originally Posted by hcoles

I may have time tomorrow to disconnect the O2 and take a ride to see if there is a change.
A transmission mechanic I know describes trailer hitching... "when you come to a stop there is a sort of clunking sound as if the transmission slipped or made some sort of shift as the vehicle "rocks" back and forth after braking." something like that

the injectors should be good - WitchHunter about 2 years ago and just ran a bottle of Techron through... car ran great at the track, wasn't even back firing sometimes on shifts come to think of it...

I always understood "trailor-hitching" as this ... a push and pull while driving at constant accleration - surging of sorts. Similar to the feeling one gets while towing a boat or other heavy item - kind of a push and pull.

[Jim Smolka]

Also, check the engine speed sensor.

[hcoles]

some progress - I went to my mechanic to visit and ask re. the surging. I was going to disconnect the O2... he said to try that first and reached in there and disconnected it for me.

The surging is almost all gone... probably where I was at or better. BUT the very interesting thing is how great the car runs now... no hesitations.... mid throttle is firm and no missing, idle is smoother... is this what I get with a Steve Wong chip? I guess my O2 is just about confirmed bad at this point... right?

Thanks for all the comments..

[PatrickB]

Originally Posted by hcoles

some progress - I went to my mechanic to visit and ask re. the surging. I was going to disconnect the O2... he said to try that first and reached in there and disconnected it for me.

The surging is almost all gone... probably where I was at or better. BUT the very interesting thing is how great the car runs now... no hesitations.... mid throttle is firm and no missing, idle is smoother... is this what I get with a Steve Wong chip? I guess my O2 is just about confirmed bad at this point... right?

Thanks for all the comments..

No... Only if you replaced the o2 sensor with a NEW one and it ran better would that confirm it as the culprit. By removing it, the mixture is running far richer than it normally would... This in turn could be masking whatever the REAL problem is.
You will also notice a dramatic increase in fuel consumption. You will likely lose as much as 3-4 miles per gallon.

[mca]

hcoles -

I would bet that most people run without the 02 sensor. Time for a poll maybe??

When I first got my car a local shop said that I needed to install an 02 sensor (was removed when previous owner installed headers) despite the fact that it was running great.

Once a new sensor was installed and hooked up, I got the surging problem. I disconnected it, the surging stopped, and I went on my way. If you have your mixture set correctly, you really don't need it.

In your case, you may be masking some other problem in the event that you still show signs of surging (even minimal) with sensor disconnected.

Keep us posted!

[hcoles]

a guy with another 3.2 that I track with has his O2 disconnected all the time also. I would like to get to the bottom of this however. I think when all is proper the car should run fairly smooth at all the part throttle positions. I need to get some energy and start looking at things. Probably the first thing is to check all the linkage and adjust. Also need to find out or relook when the "idle" switch is supposed to activate. I think this is in the Bentley or on threads here. I have a break out box for the DME - I need to put that on and look at the O2 signal.. that should tell me if it is ok or not. Will keep you posted - not much progress this weekend, it was cold around here

[paulgtr]

I used to leave the O2 sensor unplugged I thought it was the problem.
I had the trailer sysndrom at 2500 rpm in the lower gears and sometimes in 4th as well
I think it is more to do with the co2 adjustment and also the dme relay.
I replaced the relay and also installed a SW chip
did the cht sensor as well
and it runs better with the o2 sensor plugged in
granted I don't run at the track, but the response is much better now
next is to have the injectors refreshed and see how that works
I have learned to always to one thing at a time
that way you can see how it works