WHAT I'VE DONE SO FAR:

New Distributor Cap, Rotor, Spark Plugs, Wires, Ignition Coil, O2 Sensor, EGR Valve, PCV Valve and PCV Filter. The fuel filter and fuel pump were both replaced less than a year ago.


Any Ideas? The car runs fine but I want to keep it running smooth since it's getting older.

 

- Have you checked the TPS? Should be around .65V
- How many miles on the TBI? Have you rebuilt it?
- Any Codes?
- Have you tried putting the stock chip back in to see if that helps?
- Have you checked/replaced the IAC?
- Are all your wires and connectors in good condition?

 

yeah, put that stock chip back in there. See what happens. Where did you get the chip from?

 

I'll try putting the stock chip back in, but I had the aftermarket chip in there for a long time before I had this Ideling problem. I got the chip from TBIchips.com.

I haven't rebuilt the TBI since I've owned it. But I didn't think it was that important for TBI's to be rebuilt.

No the engine hasn't thrown any codes. ( The Check Engine light hasn't come on)

Is there some way to clean the IAC? How do you do that?

All they electrical connectors seem to be in good condition from what I can see.

I'll check some of this stuff out and get back to you guys. Thanks for the replies.

 

Have you checked teh CTS? Thatll cause some issues if its misreporting the temp.

 

Just to add to my previous post, it sounds like an open/closed loop problem since you state the idle screws up after it gets warm. As far as the IAC goes there is a section in the Haynes manual about servicing it, if I remember correctly; if not there try Chiltons. I'll look and get back to you. If you want to try I can scan the section and send it to you in email.

 

Well I just replaced the TPS and that didn't solve the problem.

Tommarow I'll replace the CTS, and the IAC. I'm crossing my fingers.


Thanks for all the help guys.

 

Did you make sure the TPS is reading correctly?

 

Well the TPS is new, so it should be reading correctly, right?

 

Sometimes adjustment is need; this link is to the technical article portion of this site and goes straight to IAC and TPS adjustments
Good info; however I prefer sticking sewing needles into the wires instead of jumping them; check out the link and you'll see what I mean; let me know if it doesn't work.

https://www.thirdgen.org/newdesign/tech/tpimod2.shtml

 

Today I changed my IAC Valve and my CTS, heres what happened;

First I changed the IAC. Then I started my car up (Cold). At first it started ideling really high at 2500 RPM for about 3 min. Then the idle dropped down to about 1500, and began surging up and down between 1200 and 1500. At that point I turned on the AC and the car died. After that I decided to go ahead and change the CTS Sensor. When I started my car up this time it did the same thing. It surged up and down between 1200 and 1500 then when I turned on the AC it died. I'm very frusterated.

 

I'll check that out.

 

Okay I tried the TPS and IAC adjustments but the problem is worse if anything. Now when I start the car up it doesn't even try and idle. Can any one else help me? I'm desperate.

 

Try checking your vacuum lines... i replaced some of mine and a couple 2 way check valves and my idle went from really rough to dead quiet

After you replaced all that stuff thats the only thing i could think of.

Derek

 

ECM?

 

Pump? Fuel pressure?

 

Checked the vacuum lines and even replaced a couple.

Fuel pressure is good, pump was replaced less then a year ago.


For some reason I'm starting to think this may be an electrical problem. If I can't figure out what's wrong with this thing I might have to take it to the dealer, and you know that's gonna cost $$$.

 

Have you hooked up a vacume guage to see what kind of vacume you are pulling at idle?

Do you have a scan tool? finding out what the sensors are reading, would really help to diagnose this.

Have you tried setting idle with the IAC disconnect, and in its parked status. I try to set mine to idle abou 425-450 with the IAC disconnected, so that the IAC should have enough range to stabelise the idle.

But it really sounds like a vacume leak to myself. a vacume guage and a scan tool (or laptop with winaldl on it) would really help you here.

 

Okay I finally got my hands on a "scanner" (I guess that's what you call it). The scanner said that the output voltage of the TPS is to low. But it's brand new. What could cause the TPS to put out too low of a voltage even though it's brand new?

 

Whats the voltage with the throttle closed?

 

I'm not exactly sure. I didn't scan it myself. My brother in law, who's an auto machinic for a living, did the test and told me the TPS output voltage was too low. I think it might have been something like .56 volts though.

 

Whats going on with your car now.Ive been reading this post because I have all the same symtoms that you have and have tried most of what you have and cant figure it out.

 

awhile back i had this same problem, i did exactly what everyone suggested and nothing seemed to help and it was impossible for me to keep the engine running long enough to run out and adjust the IAC and idle screw and/or the TPS. I did however place the stock chip in and turn it over, problem solved it was in my that i burned.

 

Well I still haven't figured out what's wrong with the damn thing. A scanner reading showed that the TPS output was too low eventhough it's a brand new unit. It was suggested to me that something may be impeding the voltage somewhere in the connection between the ECM and the TPS, but I can't find anything.

I will be taking it into a shop pretty soon.

I hope it doesn't cost too much $$$$.

I let you guys know how it turns out.

 

Any updates?
Looks like I am just at the beginning of the problems you are discribing.....so I am curious, did you get her fixed yet?

 

Nope still haven't figured it out yet. I've been meaning to take it to a shop, but I'm kinda tight on money right now.

When I do figure out whats wrong with it I let you guys know.

 

have you tried pulling the hose off the egr valve and see if it clears up ?

 

You mean running the car with the EGR valve off? I haven't tried that, but I did replace the EGR valve.

 

yeah unhook the vacum line to it just to be sure its not getting any vacum at idle

just unhook it and see if it helps .

 

Hey...I fixed my problem with the idle.
By process of elimination I started her up and let her get warm....as usual it started to stumble...and miss...and stall.

So I unplug the temp sensor..and the engine starts to run better....
Well the computer uses the temp sensor, and O2 sensor to adjust the spark and fuel....
Well I had plenty of fuel...cause it runs good cold.
so I change the O2 sensor....no help.
I pop the cap on the distributor...and I have about 1/8" side play in the shaft....so I change the distributor....and shabang...idle is smooth as silk...yipppeeee