ok today i finished installing my rebuilt 2.8L v6 and when i started it it sat at 2000 then jumped to 3000 then next 4000 after 5000 and was shut out before it reached 6000. it continues to auto rev up everytime the car is started all vaccume lines are connected im totally blindsided to what could be causing this idle issue please all help will be highly appreciated stock 2.8 L with comp cams 260H with 1.60:1 rolloer rockers. the engine i mated with the isuzu 5 Speed transmission please help
The only way an engine can hit rpms like that is with lots of air........I would start looking at the Throttle Body, Idle setting, throttle cables, TB butterfly return spring .
------------------ Mark ' 85 2m6 3.4PR In the Great Northwest!
[This message has been edited by NW-Fiero (edited 11-20-2014).]
today i swaped a new throttle body on with a new MAF sensor IAC sensor , the egr tube is in tach it may be leaking air thats a good start , the TB spring was turned all the way in started same result backed the spring out got the same result , i was wondering if maybe could have been the EGR canister or the EGR control valve if not maybe the computer ?? thanks again for the help i really appreciate it
the TB spring was turned all the way in started same result backed the spring out got the same result
Are you referring to the throttle stop screw?
If so, you weren't supposed to be "screwing" around with that as it was set at the factory. It'll need to be properly re-set (just off of completely closed) so that the TPS reads correctly when the factory idle speed is reached.
Thanks everyone for trying to help i really appreciate it , I'm still confused the screw that i turned , not sure of the name but its the one on top left of throttle body controlling the throttle open position i attempted the smoke test but not sure how this exactly goes but when i blew smoke into the EGR line it was coming out by the EGR solenoid when i blew smoke into the top canister hose did not find a trace, the lower hose seem to come out of the intake when i installed the EGR tube i used form a gasket does it need a actual gasket im so confused hoping i can figure out tmr what needs to be done i have a donor car so I'm hoping its fixable without pulling the engine because its my 4th time pulling it out please continue to help i really appreciate everyone who help thanks again.
the hoses by the fire wall I'm a little confused to where they connect to i have a small air filter in the valve cover , thats by the fire wall i know the line that runs from the EGR solenoid plugs into the bottom of the air box but the larger hoses are not connected, maybe its the air filter in the valve cover that is sucking so much air in ?? thanks again
yes the brake booster hose that plugs into the hose on the lower intake manifold that comes from the body of the car , thats connected not sure if its air tight
[This message has been edited by Ruffino3124 (edited 11-20-2014).]
That throttle body screw is a problem. If you have a spare throttle body that has not been messed with....use that. The vacuum lines all have to be air tight to get the idle down.
There is a metal tube that runs from the underside of the throttle body down to the intake manifold next to the cold start injector. It's easy to miss installing it and will cause a large air leak if it's not there.
------------------ Rod Schneider, Ball Ground, Ga. "You can't have too many toys!" 1988 Fiero GT 1988 Porsche 928S4 1987 Corvette 2001 Chrysler 300M Van's RV-6 airplane
Thanks again for everyones help , i just took the intake manifold off and every vaccum line is connected , i feel like my mistake was when i installed the egr tube i never used a gasket i tried form-a-gasket but air is maybe just slipping past now my next question is a vote on whats my next step EGR valve Delete? or new tube and gaskets? thanks
Thanks again for everyones help , i just took the intake manifold off and every vaccum line is connected , i feel like my mistake was when i installed the egr tube i never used a gasket i tried form-a-gasket but air is maybe just slipping past now my next question is a vote on whats my next step EGR valve Delete? or new tube and gaskets? thanks
Thanks again for everyones help , i just took the intake manifold off and every vaccum line is connected , i feel like my mistake was when i installed the egr tube i never used a gasket i tried form-a-gasket but air is maybe just slipping past now my next question is a vote on whats my next step EGR valve Delete? or new tube and gaskets? thanks
Using form-a-gasket in place of gasket should not cause enough of a vacuum leak to let it hit 5k. Try listening for air leaks with a shop stethoscope, they cost maybe $10-15. Also, be sure to listen to where your fuel injectors plug into the manifold. BTW you did use new injector O rings, right?
hey everyone today i installed the EGR valve delete kit , i checked all vacuum lines i made sure everything was connected , i used a throttle body that has not been touched , i tripple checked everything its all together in the correct way when i started it , she idled at 4000 RPM then gradually incresed by 500RPM in every 5 seconds. i shut it out didnt start it again , at this point my brain is fried , fingers are frozen from working outside, im completely confused to what i did wrong my next ideas that could possibly be the cause -fuel injectors - used from automatic transmission -fuel injoctor 0 rings -fuel injector harness - used from automatic transmission -computer - came from 4 speed manual transmission now mated with 5 speed isuzu -temperature sensor 160* using stock male connecter never sliced the new male connecter over to the manual transmission harness other than these i really dont know which direction to go please if you have any ideas or any way to help i will appreciate it more than anything at this point thanks again Ruffino.
[This message has been edited by Ruffino3124 (edited 11-28-2014).]
It's pretty hard to figure how fuel injectors could let air leak into the intake If you didn't replace the intake to injector o-rings or they are not seated in place this maybe the problem. The injector harness won't let air into the intake manifold Both the automatic and manual ECM won't idle the engine at 5,000. The temperature sensor won't let air into the intake manifold
Unplug and remove the IAC, stick your finger in the hole the IAC hole covering the port that leads to the engine. Start the engine. If the engine is over-reving the problem is a vacuum leak issue. If the engine won't run with this hole covered then the problem is that the ECM isn't able to control the IAC.
[This message has been edited by phonedawgz (edited 11-28-2014).]
Phonedawgs thank you so much you have been a helpful member on this forum i just want to let you know that i appreciate it , the EGR valve kit delete is this - http://www.blacktopupgrades...lock-off-kit-2-8-v6/ and i never changed the O rings when i replaced the fuel system i just cleaned everything and I'm most likely going to try your method tmr the ECM that i am using came from a same year pontiac fiero gt it was a 1985 v6 with a 4 speed manual ECM the setup that I'm trying to run is 1985 v6 isuzu 5 speed could it possibly be the ECM
Alright today I tried to attempt to figure the main problem after a couple of trys I found out that when I started it and had a friend cover the port inside the throttle body leading to the IAC the engine idled down to 3000 then slowly dropped with in a minute it dropped to a stall. So I thought that it had to be the IAC not controlling the air I switched to a new one but had the same result I'm not sure if im I installing it right or maybe if its a clogged vacuum port because everything is connected please if there's any help that anyone can offer I will appreciate it to the max , thank you all for hanging In there with me.
The IAC pintle can be jammed if it is overextended when installed.
--- When you cover the IAC feed hole in the throttle body the engine speed response should be as quick as it is when you close the throttle. HMMMMMMMMM. ----
Plug in your second IAC and hold it in your hand. Block the pintle from over extending because it will pop free out of the IAC. It is fine to block the movement of the pintle. Start the engine and have your assistant control the idle speed.
Does the ECM extend the pintle when the idle speed is too high? It should. Does the ECM retract the pintle when the idle speed is too slow? It should.
They do go over testing the IAC wiring in this video.
[This message has been edited by phonedawgz (edited 11-30-2014).]
hey so i wasnt able to run all the tests i would like because of the snow still currently trying to gt the car running right so i can move it into my garage so i can continue working on it just want to say thanks again to all that has helped so far i was able to run the car on a different ecu to see if it was a computer or prom issue but turns out it ran the same i did one more smoke test and smoke only came out of the throttle body , a lot of smoke -------possibly faulty TB ? after i checked the check engine light and there was no bulb so i put a bulb in and at first there was no codes after i started the car 2 code came immediately CODE 22 and CODE 23 hopefully that is enough infornmation to fix my idle if you have any ideas as to what could be the main cause i would really appreciate it will continue testing the iac on better weather terms thanks again
[This message has been edited by Ruffino3124 (edited 12-10-2014).]
today i was able to run the car constantly i noticed the ecm light comes on and goes out , sometimes it stays out for a long time but im not understanding it because another code came up all my codes are CODE 22 CODE 23 CODE 33 i changed the tps sensor to another one i had from a different throttle body but the car was still idling up to 5k RPMs , when i cover the iac port it de idles to 2k i noticed today when i cover the whole throttle body opening the car stalls right away could it possibly be a bad TB leaking too much air in past butterfly the suction leading to the iac in the throttle body is very strong , you can hear it when i start the engine or when i stop covering it i also did a light test on the connecters TPS- the only wire that made the light glow was the grey wire one that carried a positive feed - should the other two ones glow also the IAC connecter- only two pins made the light go off it was both blue wires - should all the pins light up on the IAC ?? please if anyone knows whats going on or ever had this combination all help will be highly appreciated.
this is a video of me covering the IAC por leading to TB this is a better look at whats going on please any comments and all help will be appreciated thanks again
[This message has been edited by Ruffino3124 (edited 12-11-2014).]
You have more issues than just a high idle...Is that a race cam you installed?..kinda hard to tell where the idle is..... Look around the MAP sensor for a loose or missing vacuum tube....sometimes they look good but are not completely snug....
The throttle body has a "set screw" that many people mistake for an idle adjustment screw....but it is not. It was pre-set at the factory and some sealer went on top of it to cover it up...
If you can see the screw head on your throttle body, it has been tampered with somewhere along the line, and needs to be corrected.
thank you again for helping me out i believe it is the racing cam 260H comp cams with the 1.6 roller rocker arms to match the cams do you know where i can get a ecu that can run that camshaft or should i contact comp cams?? the TB that im using is from a 2.8 automatic but there is no screw to adjust the idle its just flat metal in that area where it would be if you need any pictures i can post on Photobucket and add the link. not sure how to post pictures on this forum i tried many times never works for me. i ordered a stock oem throttle body im hoping that will give some type of a fix the MAP sensor is all connected in im not sure why the engine continues to rev up on its own it will reach 6k RPM if left running by alone when i cover the iac port it starts to idle around 3k RPM tomorrow im going to run a volt test to see if the sensors are getting the correct voltage or if i have faulty connecters Thanks again to all that are helping Ruffino.
[This message has been edited by Ruffino3124 (edited 12-15-2014).]
i have two throttle bodys one is from a 4 speed , the other from a automatic i switched them at one point turned the screw in on the 4 speed one and the condition got worse. so i put the automatic TB back on and it still is reving up on its own , the automatic TB is flat where the screw would be i dont think the auto one i have is able to be adjusted
I don't have an automatic Fiero, so I can't be sure, but I have not heard of any Fiero throttle body that does not have that set screw. Could that TB be from another car?
the automatic TB is flat where the screw would be i dont think the auto one i have is able to be adjusted
That's because the "tamper prevention" cover is still in place over the idle adjustment/set screw. All Fiero TBs originally have that cover in place from the factory. The cover (and set screw underneath) shouldn't be messed with.
quote
Originally posted by Ruffino3124:
it will reach 6k RPM if left running by alone when i cover the iac port it starts to idle around 3k RPM
You've obviously still got a big air leak somewhere in the intake system.
[This message has been edited by Patrick (edited 12-15-2014).]
MAP-grey wire- 5.057 green wire-0.019 black/red- 0.007
this is the volts that is being sent out while the car is in the on position engine off if you notice a problem with the volts please lend me some advice the one that looks completely off is the IAC - for the iac all of them should have 5 volts i dont understand it thanks again for helping Ruffino.
[This message has been edited by Ruffino3124 (edited 12-15-2014).]
Phonedawgs thank you so much you have been a helpful member on this forum i just want to let you know that i appreciate it , the EGR valve kit delete is this - http://www.blacktopupgrades...lock-off-kit-2-8-v6/ and i never changed the O rings when i replaced the fuel system i just cleaned everything and I'm most likely going to try your method tmr the ECM that i am using came from a same year pontiac fiero gt it was a 1985 v6 with a 4 speed manual ECM the setup that I'm trying to run is 1985 v6 isuzu 5 speed could it possibly be the ECM
If you pulled the injectors and did not put new O rings on them it's a good bet at least some of are leaking air. You need to install new O rings else... BTW the cost less than $10. You can try putting some dextron them overnight to soften the old ones up, but you really need new ones.
im back once again merry late christmas , i dropped the engine out to check everything again and made sure all vacuum lines were connected and working. i installed new o-rings / a new coolant temperature sensor / new throttle body. when i started the car still recieved the same result and still flashed the CEL code 22 and 23. i have done almost eveerything that i could possibly do to fix this problem. please if anyone on this forum is using 260H comp cams please tell me if you can use the stock ECM with them or do you need a different computer. the pressure in the crankcase is whats causing such a high vacuum sucking into the valve cover by the firewall when i cover that port it idles down to about 2000RPM today i watched the rpm go down to 900RPM but then jump back up to 2000RPM please if you have any idea as to why this is happening please help i love this car thanks again
Alright today I tried to attempt to figure the main problem after a couple of trys I found out that when I started it and had a friend cover the port inside the throttle body leading to the IAC the engine idled down to 3000 then slowly dropped with in a minute it dropped to a stall. So I thought that it had to be the IAC not controlling the air I switched to a new one but had the same result I'm not sure if im I installing it right or maybe if its a clogged vacuum port because everything is connected please if there's any help that anyone can offer I will appreciate it to the max , thank you all for hanging In there with me.
Call me crazy but I think you found your answer. Even new iac's have to be adjusted. My instructions said that it should extend no more than 1-1/8" from the face of the gasket (I set mine right at 1-1/8"). Pull it and check the measurement and reset it if required. After you drive the car over 40 mph (hold a steady speed I think) for more than 1 minute, the ecm will do a final adjustment and set the idle. The other thing I thought of that's also been mentioned is the large vacuum line that plugs into the manifold side of the throttle body. I forgot to attach it on mine and the idle was really high. It's an easy one to miss and a difficult one to put on, I had to take off the throttle body to do it.
[This message has been edited by countach711 (edited 12-29-2014).]
