Few issues after installation of pacesetter header
 

Hi Guys
I've recently exchanged my old exhaust system with a set of pacesetter header, a new cat converter and a dynomax exhaust (I had it before). At the same time I've replaced my EGR valve and removed the Air injector (no choice with the header)
I've since few issues with the way the motor is running :
- the motor is hesitating when the gas pedal is slightly depressed. No issue at WOT. If I disconnect the vacuum pipe on the EGR the motor run much better.
- When I release the gas the motor increase RPM to around 2000 before going donw to idle (700 RPM). It was not the case before. If I unplug the IAC, the motor run around 2200 RPM, is it normal?
I've checked for vacuum leak : every think is fine.
I've checked the timing. 22° with EST connected and it doesn't change when the EST is deconnected. I don't untestand why. I've tried to shorten A and B on the ALDL connector, no change still 22° When I increase RPM the timing increase to 35°

Do you have any idea on what could be wrong?

Re: Few issues after installation of pacesetter header
 

You need to set timing with est disconnected. I'm about to install headers myself hopefully I don't run into those same issues. I dont have egr on my car and runs good. But I am thinling of reinstalling when I instal the headers. I'll see.

Re: Few issues after installation of pacesetter header
 

Re: Few issues after installation of pacesetter header
 

Do you have an automatic or manual transmission?
- Unplugging the IAC will likely cause the RPMs to do something odd since the ECM doesn't know where the throttle position is at, so it defaults to a given setting.
- Your timing is off if it's at 22 with the EST disconnected. It should be at 10°. Disconnect it, set it to 10°, then plug the wire back in. Make sure you do it with the engine at operating temp. It is normal for your timing to advance when you raise the RPMs.
- When you removed the AIR pump, did you remove everything associated with it and cap off any vacuum lines? You may have a vacuum leak, make sure you didn't crack/break any vacuum lines. You can find that by spraying carb cleaner around and listen for RPMs to change.

Re: Few issues after installation of pacesetter header
 

I have a manual transmission
- if I disconnect the EST there is NO effect. The timing stays at 22°. This is the issue. This is the reason why I'm asking if it could come from the ICM
- I've removed everything linked to air pump and capped the vacuum line. I've verified that there is no leak on the vacuum (both with the gage and by spraying cleaner fluid)

Re: Few issues after installation of pacesetter header
 

It could be an issue with the module. Have you tried resetting your base timing, will it go to 10 and run well? Do you have high mileage on the timing chain? This could also be causing a timing issue. First thing I'd try is moving the distributor, resetting the base timing to 10 and see how the engine runs. If it runs horrible, then look at maybe an ICM (cheaper and easier) or possibly a worn timing chain.

Re: Few issues after installation of pacesetter header
 

If I move the distributor and set the timing to 10° the motor runs poorly : no torque at all. Not surprising as the EST doesn't seems to work as it should be (increase the timing). that's the reason why the base timing is now at 22°
The timing chain as only 67 kmiles. The timing is pretty stable at idle.

Re: Few issues after installation of pacesetter header
 

Everything was fine until you installed headers, replaced the EGR valve and removed the AIR? You had none of these issues before? I just want to make sure we're chasing the correct issue here

Have you checked for a leak around the EGR valve or around the headers? Also, have you checked to see if you have any codes set? If all you did was headers, EGR and AIR delete, your timing shouldn't be affected, which makes me think you had a previous issue.
What was your reason for replacing the EGR valve?

Re: Few issues after installation of pacesetter header
 

Everything was fine but the timing issue was definitly there before as I havn't touched the distributor during the installation of the headers.I've seen it because I'm tryng to chase all the possible problems.
I've checked leaks and nothing around the EGR or the headers.
No code set.
I replaced the valve because I had isues to remove the old one from the exhaust.

Re: Few issues after installation of pacesetter header
 

Check which connector you are opening, should be in this general area:

https://www.thirdgen.org/forums/dfi-...ml#post6251601

RBob.

Re: Few issues after installation of pacesetter header
 

Re: Few issues after installation of pacesetter header
 

OK, sounds like the ICM is bad. At a minimum it is clamping the EST signal, as that is what the ECM sees to set code 42.

RBob.

Re: Few issues after installation of pacesetter header
 

I highly recommend spending the extra on an AC Delco ICM

Re: Few issues after installation of pacesetter header
 

I have an old icm that was on a working distributor. I will make a try and see if it solves the timing issue.

Re: Few issues after installation of pacesetter header
 

Re: Few issues after installation of pacesetter header
 

that was the same on mine
you need a heated o2 sensor from an s10 or trailblazer the ing plus you take from the fuel pump relay

Re: Few issues after installation of pacesetter header
 

That's strange. I've checked the O2 sensor and everything seems to be OK. The loop is closed most of time (except at idle after 1 min or so) and the signal on the aldl tool seems to be perfectly fine.

Re: Few issues after installation of pacesetter header
 

so i read that the exhaust gases wont get hot enough for the standard o2 sensor to work properly
mine did the same thing
besides that the gaskets that are included in the kit are not good they leak almost immediately better you use the FEL-PRO MS90864 gaskets
check for a stuck egr valve maybe you need a iac relearn
mine stall all the time when i shift into reverse because of the iac valve

Re: Few issues after installation of pacesetter header
 

It seems that nobrody has exactly the same beahvior for the o2 sensor. Seems to be better with ceramic coated headers. In my case as the system is going in closed loop I assume that the sensor is hot enough but I may be wrong.
I put some FEL PRO gaskets but it starts to leak again on the cylender closer to firewall. I will change the gasket and put some RTV seal.
The EGR is new but could have some issue with the calibration (they are using a washer to calibrate the gas flow). I will try to put back the old one.
How do you perform the IAC relearn?
Any thought about the reading of the coolant sensor ?

Re: Few issues after installation of pacesetter header
 

I remember long ago reading that people convert to a heated 02 sensor after installing headers on these things.

Re: Few issues after installation of pacesetter header
 

you can block of the egr with a plate to test if it run fine or get uncontrolled exhaust gas to the intake manifold
well if it dont run well its never a mistake to change all the sensors on a 29+ year old car
to reset the iac there are detailed steps on this forum
but i think its only a exhaust leak you have one in the back but maybe there are a few more you cant see

Re: Few issues after installation of pacesetter header
 

I will change the gasket and see how it behaves.
Most of the sensor have been already changed (coolant, air, maf...)

Re: Few issues after installation of pacesetter header
 

When I installed the Pacesetter headers on mine, I also used the FelPro gaskets, ditched the ones they came with. I never had an O2 sensor issue, never had to install a heated O2. I had block off plates for my EGR. Fairly simple to cut and install.

Re: Few issues after installation of pacesetter header
 

You have a new eprom with the EGR cancelled or you are running with the standard one?

Re: Few issues after installation of pacesetter header
 

Had the stock ECM. Had plans of burning a new chip with some mods, but never got to it and ended up going V8. Still wish I hadn't lol.

Re: Few issues after installation of pacesetter header
 

wish you hadn't gone v8?

Re: Few issues after installation of pacesetter header
 

Yeah, the V6 was more fun. The V8 was a carbed budget build. I was starting to get parts together to switch it over to TPI, then came across a 98 Formula and ended up selling the Camaro. Had I stayed with the V6, I may have kept it and gone w/ the hybrid swap, or turbo.

Re: Few issues after installation of pacesetter header
 

And you had no errors on the ECM. When I just disconnect the vacuum port on the EGR I have an error after running few kms.

Re: Few issues after installation of pacesetter header
 

lol no, I had the check engine light come on as soon as I'd hit cruising speed and warmed up. I was going to wait until I had a proper tune to take care of it. I didn't want to waste $$ on a chip just to turn EGR off. I was going to do it/have it done all in one shot.