ok so we finally got my motor started today while working on my 2.3 n/a to turbo conversion... and when she starts it starts fine, but then the revs go all the way up to the limiter. weve checked the throttle cable to make sure it wasnt stuck or something... and also at the vacuum lines to make sure there are no leaks (to my understanding vacuum leaks wouldnt drive the revs all the way up though)... so does any one have any ideas as to what might be going on? just drop em out there so i can troubleshoot them on the car. thanks in advance.
motor problem
- Thread starter syanyde
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Yeah something is obviously messed up to make it do that....something physical like the throttle blade being open, I don't even think the idle air bypass could let enough air by to do that.
do you think that because we deleted the EGR off it might have anythign to do with it? my understanding of egr is that it is just emissions stuff.. we took the air intake manifold off, and had to weld a bead into the opening for where the egr mounted up, but that bead should be solid so there shouldnt be any leak there.. ill have to go check on my throttle itself since did have that off, but with the cables still connected
This may be a stupid question, but I'm going to ask it anyway. When you mentioned that you hadn't touched the ECU, did you mean the original N/A ECU or have you repinned and installed the Turbo ECU?
Check your wiring and repin job if you haven't already. It seems like the ECU is getting bad info from somewhere. My guess would be TPI or VAM wiring either at the sensor or at the ECU plug.
Check your wiring and repin job if you haven't already. It seems like the ECU is getting bad info from somewhere. My guess would be TPI or VAM wiring either at the sensor or at the ECU plug.
thats what i was thinking that the ecu is maybe confused, but heres the deal. its the stock ecu for the n/a motor, im using a FMU to control the fuel so the car shouldnt have any issues.. because im not even in boost yet. when you start the car up, it revs all the way to the red line.. doesnt sit and idle first then go, it goes straight to the top. now all this happens only when the air is being routed through the turbo, when we hook the MAF and air filter straight to the throttle/air intake manifold the car responds normally.. as in it just idles. we have no idea what is going on with this, the car should run fine at idle with the turbo installed.
zoomin
Founding Member
havent been into the turbo cars in a while but this is a longshot. how is your wastegate actautor are you running any sory of boost controller? the only thing i could think of is that ur turbo is building boost and pushing ur throttle plate open. when it revs up does the butterfly open, like can you see the cable move as if you were to floor it? so ur running a stock non turbo computer and you have a MAF so its a 91+ rite? where in the system do you have the MAF setup before boost of after?
and guys if that was a stupid guess dont laugh, lol.
later
victor
and guys if that was a stupid guess dont laugh, lol.
later
victor
im leaning towards the EGR valve right now, i think the computer is confused because it thinks the EGR is still hooked up and open all the way. what ive been reading is that when there is a problem with an EGR valve it acts like a huge vacuum leak and when you have a vacuum leak, you get high revs with out being on the throttle...
zoomin said:
im running a boost controller so i will check that. my maf is right after the cone filter, so its before the turbo. and yes the car is a 92 with a stock ecu. to the best of my knowledge though i should have no issues with my current set up with the car sitting at idle. when i get into boost that will be a different story, but at this time i cant even test for that
Okay, now I understand. I was under the impression you didn't have a MAF at all.
If there's no EGR valve in place anymore and the flange is blocked off, there's no vacuum leak from a wide open valve. The EGR position sensor may be reporting that the valve is wide open, but it still won't make it rev like you're saying.
Something to think about, if you can't see the throttle blades moving like zoomin said, check the IAC. If the wastegate actuator is stuck, or being held shut and you're building boost at idle, it may not be enough to push the throttle blades open ,but it may push a worn out IAC valve off of it's seat. Once it does that, there wouldn't be enough pressure to push the throttle blades open anyway. I can't say that I've seen or heard of it happening, but it's the only other way I can think of off hand that air could get by like that. Again, this is only if you are actually building boost at idle.
If there's no EGR valve in place anymore and the flange is blocked off, there's no vacuum leak from a wide open valve. The EGR position sensor may be reporting that the valve is wide open, but it still won't make it rev like you're saying.
Something to think about, if you can't see the throttle blades moving like zoomin said, check the IAC. If the wastegate actuator is stuck, or being held shut and you're building boost at idle, it may not be enough to push the throttle blades open ,but it may push a worn out IAC valve off of it's seat. Once it does that, there wouldn't be enough pressure to push the throttle blades open anyway. I can't say that I've seen or heard of it happening, but it's the only other way I can think of off hand that air could get by like that. Again, this is only if you are actually building boost at idle.
zoomin
Founding Member
even with boost i dont think enough air could get through the IAC to take the revs to the limiter, when you ran the car with the n/a intake setup could you feel the turbo building boost? check the waste gate actuator and if the lines to it are setup correctly, if it was building boost could it actually push the butterfly open?
victor
victor
Brantley
Founding Member
Couple points...
You're not going to get very far with the stock computer. You need a turbocoupe ECM, VAM, and fuel injectors. You might be able to get it to run ok off boost, but when you are into boost, your timing and fuel will be way off. As long as you are content with a low power output, or a lot of redneck engineered band-aids, you'll be ok.
Next time you fire up the car when running thru the turbo, just unplug the connector off the IAC. If that doesn't make a difference, next I would remove the IAC all together, and do something to plug the holes so that you know they are blocked. Also, don't just think the throttle body is closed, use your hand and force it in the closed position. Dosconnect the throttle cable. Basically, a lot of extra air is getting into the engine, and you have to figure out where & why. What is different about going thru only the MAF, and then putting the turbo in the system? Are you using any different pipes? Connectors? Go through each component.
EGR shouldn't affect it at all. EGR recirculates exhaust gas back into the cylinders are cruise conditions in order to reduce NOx emissions. EGR does not function at idle or WOT. Yes, it could fail in a way to cause a big vacuum leak, but it can also fail in a way that it will never work. Either way, since you no longer have it, it doesn't matter. What does matter is to be absolutely sure the flange on the intake manifold is blocked off and air tight.
Unless that turbo is extrememly tiny or you have an auto tranny, I seriously doubt you'll be building boost while revving with no load. Possible, but quite unlikely.
You're not going to get very far with the stock computer. You need a turbocoupe ECM, VAM, and fuel injectors. You might be able to get it to run ok off boost, but when you are into boost, your timing and fuel will be way off. As long as you are content with a low power output, or a lot of redneck engineered band-aids, you'll be ok.
Next time you fire up the car when running thru the turbo, just unplug the connector off the IAC. If that doesn't make a difference, next I would remove the IAC all together, and do something to plug the holes so that you know they are blocked. Also, don't just think the throttle body is closed, use your hand and force it in the closed position. Dosconnect the throttle cable. Basically, a lot of extra air is getting into the engine, and you have to figure out where & why. What is different about going thru only the MAF, and then putting the turbo in the system? Are you using any different pipes? Connectors? Go through each component.
EGR shouldn't affect it at all. EGR recirculates exhaust gas back into the cylinders are cruise conditions in order to reduce NOx emissions. EGR does not function at idle or WOT. Yes, it could fail in a way to cause a big vacuum leak, but it can also fail in a way that it will never work. Either way, since you no longer have it, it doesn't matter. What does matter is to be absolutely sure the flange on the intake manifold is blocked off and air tight.
Unless that turbo is extrememly tiny or you have an auto tranny, I seriously doubt you'll be building boost while revving with no load. Possible, but quite unlikely.
yeah i know about all the things i need to get in terms of ecm vam and injectors. injectors i have planned, but really running an FMU takes pretty decent control over my fueling. all im looking to do at this point is to get the car started and running normally at idle. im not even worried about the boost side of things yet, i can take care of that tuning later on my own. the turbo is a t3 45 trim and its on a 5 speed, so i know its not building boost, as my gauge is not reading anything... theres something else that is causing the leak (so i think it is now). ive been reassured by a local friend/mechanic that said the egr shouldnt do anything if its removed. anyways i have some things that we are going to try out.. but this is only the beginning of a lot of things to come on the car, i just need to get the car back and fired up so i can at least drive it normally.
88stangmangt
Active Member
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