When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
From the category of should have left well enough alone, I submit this.
89 IROC Z Convertible. 305 TPI Auto. Nothing fancy.
It was running pretty darn well. Of course, I decided that I did not like the 225 degree operating temperature. Went to Summit auto and bought:
1) New Thermostat
2) New Fan Switch
3) Jet Performance Stage 1 chip (which I was told was to actuate the fans at the lower temp).
Drained and flush system. Put the thermostat and new fan switch in. No leaks. For the record, battery completely disconnected, both positive and negative cables.
Installed chip, reconnected battery, started it up and idle is at 3000 rpms. Never been that high. Check Engine light also immediately comes on. I let is warm up for about 10 minutes thinking the idle would come down. It never did.
Disconnected battery again to see if it needed to reset. That did no good.
Thought maybe I needed to take a test run. Put it in reverse, it sputtered and died. Managed to back it out of garage, put in drive, sputtering and trying to die, wouldn't go.
Take OUT Jet Performance chip. Poof, back to normal.
Drive into town, let it idle, fans don't come on until 227, like before.
Drive 30 miles from garage to home, no problems, runs like a dream.
Start car today, go to local auto parts store to return misc stuff, no problem. Start up and start driving home, check engine light comes on and when I come to a stop, idles like it's missing and tries to die.
Get home, idle up around 2250 rpms and BOTH of my fans are on.
Drive back to auto parts store, they can't get any codes to come up. Store manager suggests unplugging Idle Air Control Valve, and doing so does not change the high idle. Replace valve.
Idle drops to about 1350-1400, drops to 1100 in gear, Service Engine Soon light still on. This idle is about 450rpm's higher than it was on both ends before the SERVICE ENGINE SOON light came on.
Also, what recommendations do any of you have for a 3rd Gen mechanic in the Everett, Mukilteo, Lynnwood area. I don't care if they work out of their garage as long as they really know 3rd Gen IROC's
Thank you for taking the time to answer. It is really appreciated.
I had actually pulled the Jet Chip out the same day I installed it. As I mentioned, it did run fine after that.
However, the next day, boom, all of a sudden it started sputtering and the idle went way up, and of course the SES light came on.
First suggestion (as the local parts store couldn't get it's machine to read the computer) was to replace the IAC. I did that and it helped a little.
Finally took it to a shop that I had dealt with prior, they had replaced the TPS sensor a few months ago, when it had gone bad.
They do have a machine (5 grand worth) that read the code. Seems the Borg-Warner TPS module they used in the replacement went bad. This time they installed the DELCO module and it seems to be back to it's good old self. I only picked it up this morning.... so the jury is still out.
Here she is getting new shocks and brakes at my brother in law's shop in Vancouver, Canada.
You don't need a 5k machine to "pull the codes", a laptop, ALDL cable and TunerPro will allow you see every parameter the ECM is seeing. Even then, a paper clip will pull the codes.
I know you replaced the Jet chip with the original, but my point was that the Jet chip is junk and to try re-seating the original MEMCAL as it sounded like the car was in limp home mode.
However, as I said before, the jury was still out with the latest update. Driving it yesterday what I still noticed was:
1) It still seems like every once in a while it misses, only the misses are big.
2) The transmission is randomly shifting up. Example: Driving on flat stretch on the freeway. Car is in what I would call the overdrive gear. Then, with no change in grade, it will jump up a gear. So I go from 22rpm to 26rpm and then it shifts back down.
This morning, started up just fine, but was missing and it died twice just trying to get out of the housing development I live in. Everything else seems normal. The idle is back at 750rpms, which is where it was, and there is no SES light coming on.
I have read here that this could mean the TPS isn't quite adjusted correctly. At any rate, back into the shop on Monday morning.
Since I see a number of posts on here without a solution to their individual challenge, I wanted to make sure and post what happened with mine.
Turns out all these problems were caused by the 3 wire connection to the TPS.
It seems that after 25 years of being in a hot engine compartment, and probably having been disconnected more than a few times, the wires in the 3 prong pig tail simply gave up the ghost.
My mechanic showed me the twisted pig tail, and then the 1 or 2 strands of wire left inside the positive pig tail.
He replaced it and she is now running like a million bucks.
If anyone is looking for a reasonably priced mechanic in the north end of Seattle, or the Everett vicinity, check out Meridian Towing, in Mukilteo.
08-07-2016, 07:12 PM
