89 idle issues
Thread Starter
Instructor
Joined: Apr 2011
Posts: 160
Likes: 0
From: Edinburg Tx
intake on, new vacuum lines, and after it got to about 180 deg, started up again. Man its driving me crazy. injectors maybe? saw a set on fleabay cheap rebuilt bosch 3s, any ideas? you guys have plenty of knowledge here im sure u guys can help me find issue.
Team Owner
Joined: Jan 2003
Posts: 20,292
Likes: 239
From: Summerland B.C. Canada
You may want to ohm test your injectors and test your fuel pressure for any leak down at injectors.
Here is a link to Jon's videos on ohm testing and spray patterns, etc.http://forums.corvetteforum.com/c4-t...questions.html
Here is some info on testing fuel pressure from my 86 FSM
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
Have you ever tried to set the minimum idle and TPS idle voltage ?
Here is some info on that.
http://www.lbfun.com/warehouse/tech_...ch%20Paper.pdf
Here is a link to Jon's videos on ohm testing and spray patterns, etc.http://forums.corvetteforum.com/c4-t...questions.html
Here is some info on testing fuel pressure from my 86 FSM
http://members.shaw.ca/corvette86/Fu...mDiagnosis.pdf
Have you ever tried to set the minimum idle and TPS idle voltage ?
Here is some info on that.
http://www.lbfun.com/warehouse/tech_...ch%20Paper.pdf
Racer
Joined: Sep 2005
Posts: 353
Likes: 6
From: Hamilton Ohio
My 89 would hunt from about 500 RPM to 700 RPM after it was warm. I clamped the two air hoses going to the exhaust manifolds and the problem stopped. I purchased a kit to remove the A.I.R. pump and plugged off the threaded ports on the exhaust manifolds and the engine idles very smooth now. I run this car hard during One Lap of America and was told that if the A.I.R. pump would fail I would have a hard time finding one so taking it off was a good move for two reasons. Just my .o2 worth. JD
Thread Starter
Instructor
Joined: Apr 2011
Posts: 160
Likes: 0
From: Edinburg Tx
quick update, still doin same thing code 33 has been fixed and went back to a 44. checked FP and its at a constant 45 with key on. 35 when car is idling normal and 40 when rpms shoot up. what could this be bad injectors not spraying fuel causing FP to jump from 35 to 40?? anybody get those bidding site injectors? at this point any ideas would help
Racer
Joined: Nov 2010
Posts: 476
Likes: 4
I still believe your problem lies with the ECM. I know you changed it, but are you SURE the new one isn't bad? They can be found fairly easily, and not to hard on the wallet. Might be worth a try to change it out with a new/rebuilt or good used unit.
Race Director
Joined: Nov 2003
Posts: 12,220
Likes: 446
From: Overland Park Kansas
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Did you correctly set your new TPS and IAC?
Thread Starter
Instructor
Joined: Apr 2011
Posts: 160
Likes: 0
From: Edinburg Tx
tps set, iac read ir needs to be 1 1/8" or so out, is that correct? also FP went down to 20 after an hour or so are they suppose to do that? ECM is new and i thought it wouldnt throw a code if it was bad.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
Thread Starter
Instructor
Joined: Apr 2011
Posts: 160
Likes: 0
From: Edinburg Tx
bad weather and work so haven't been able to mess with the cat but i found these wires that have been cut. can anyone pleas tell me where they go and to what, any help would be appreciated.
[IMG]
[/IMG]
[IMG]
[/IMG]
[IMG]
[/IMG]
[IMG]
[/IMG]
[IMG]
[/IMG][IMG]
[/IMG][IMG]
[/IMG][IMG]
[/IMG]
Intermediate
Joined: Jan 2012
Posts: 29
Likes: 0
From: thayer missouri
wires
those appear to be the leads for the diverter valve, air switching valve and possibly the egr valve. if you dont have the chip that sends the correct values to the ecm it is not going to run right. check and make sure the coolant temp sender is connected and working properly. just my two cents worth. last week i had removed all the above components and air pump, plugged the air tubes. i had gotten a chip from tpis prior to that so i didnt have to mess with the codes or ses light. all seems to be working fine. also make sure u dont have a vacume leak on the intake itself.
Jim
Jim
Thread Starter
Instructor
Joined: Apr 2011
Posts: 160
Likes: 0
From: Edinburg Tx
on the drivers side? all those mentioned above are connected but i will definitely look at those wires. anybody w/ a l98 that can check those wires on drivers side would be awesome. let me know and thanks
Thread Starter
Instructor
Joined: Apr 2011
Posts: 160
Likes: 0
From: Edinburg Tx
thank you woody!! haha sounds funny but man your right, PO or PPO spliced into pass side injectors and ran wires to drivers side. i feel this is my problem!! Finally something that looks like its the issue and just is time for the weekend! i knew i could count on the forum members for help. i will keep u guys posted as soon as i paste wires back together
Thread Starter
Instructor
Joined: Apr 2011
Posts: 160
Likes: 0
From: Edinburg Tx
well ran the wires for the injectors since they were cut, worked great for the last 2 days been driving a few miles at a time, today got home from work and thought imma turn this guy on, and bam it started again. im ready to start pullin my hairs out, anyone else have ideas?
Intermediate
Joined: Jan 2012
Posts: 29
Likes: 0
From: thayer missouri
Obviously there was a reason why the guy ran them off the other side. do u have a fsm with the elect supplement. if not u need to get one. that is the only way u are going to be able to figure this out. have u disconnected the ground on the back of the block. u need to clean it and reconnect it.there are 4 or 5 different things grounded there. seems there is probably a streched wire in the injector harness where it goes back to the ecm. gey a good multimeter and a few feet of wire and start cking the fuel system .
Thread Starter
Instructor
Joined: Apr 2011
Posts: 160
Likes: 0
From: Edinburg Tx
i dont have an fsm, i am looking for one though. where are the grounds located? how would i check fuel system w/ multimeter? also do u beleive it can be something clogging the lines or injectors being bad? last two days it didnt have ses light but as soon as it idles off i get the 44
Intermediate
Joined: Jan 2012
Posts: 29
Likes: 0
From: thayer missouri
When i said ck the fuel system i meant the elect side of it not pressure. earlier in this thread slmeone said to ck the ecm. when u changed the ecm was there a chip attached to the prom? po might have something else disconcted the the old ecm was calibrated for.
Intermediate
Joined: Jan 2012
Posts: 29
Likes: 0
From: thayer missouri
Dude, guessing and throwing parts at it is going to get expensive! google corvette factory service manual and order one. 100 bucks or so. wait for it to come in the mail. and troubleshoot it right. sucks to have to look at the car in the driveway not working. but u will save yourself alot of agrivation.