Help...Revving Too High
08-11-10, 09:36 AM
#1
Help...Revving Too High
I've got a 1987 NA GXL. It is pretty much stock and has always run great...
But today it is revving like crazy at 5000-6000rmp and won't back down. If I gun it, it just goes higher. When I throw it in gear and let out the clutch, it will lug and thus the revs will drop down slightly. When I push in the clutch to shift, it revs to redline while I shift. If I work the brake and the clutch together, I can manage to bring down the revs, but I'm burning the clutch and the brakes the whole time. The car is now sitting in my driveway...almost undriveable obviously.
For years, the car has been great. But last week I decided to replace the stock air box with a cone filter. The car ran alright, but there was no improvement because it was sucking hot air from the engine. So last night I started to work on a cold air intake design. I pulled the MAF out and tried to envision some options. At the end of the day, I decided to put the stock air box back in.
So this morning, I jumped in the car and it started and idled normal (cold). As I drove down the road about 2 miles with cruise on, it started to sputter. As I got to the intersection and slowed down, it stalled. I had a hard time starting it...it seemed like there was too much or not enough of something. The revs seemed a little high; 4000rpm at idle, but I thought it would settle down as I drove on. But the car did not settle down. So at the next intersection, I thought I would redline it in first gear, just to blow the excess fuel out or loosen up whatever was stuck. Well it redlined...and never came down. I shifted to second and to third and just worked the brake and clutch until I found a parking lot. The car was revving like crazy at idle, so I shut it down. I popped the hood to check if the throttle cable came off or if the 5th and 6th ports were stuck. I let the car cool for 10 minutes, but when I started it, the car revved again, so I took it directly home and got my other car. And now I'm at work, all confused.
Can someone help me troubleshoot this? I don't want to jump to any conclusions, but I think the problem is with the MAF itself or the cable connector. You see, I think I made a booboo by unplugging and replugging it yesterday while the battery was still live. I don't know what to do next. How can I diagnose this?
Also, the car really stinks now.
But today it is revving like crazy at 5000-6000rmp and won't back down. If I gun it, it just goes higher. When I throw it in gear and let out the clutch, it will lug and thus the revs will drop down slightly. When I push in the clutch to shift, it revs to redline while I shift. If I work the brake and the clutch together, I can manage to bring down the revs, but I'm burning the clutch and the brakes the whole time. The car is now sitting in my driveway...almost undriveable obviously.
For years, the car has been great. But last week I decided to replace the stock air box with a cone filter. The car ran alright, but there was no improvement because it was sucking hot air from the engine. So last night I started to work on a cold air intake design. I pulled the MAF out and tried to envision some options. At the end of the day, I decided to put the stock air box back in.
So this morning, I jumped in the car and it started and idled normal (cold). As I drove down the road about 2 miles with cruise on, it started to sputter. As I got to the intersection and slowed down, it stalled. I had a hard time starting it...it seemed like there was too much or not enough of something. The revs seemed a little high; 4000rpm at idle, but I thought it would settle down as I drove on. But the car did not settle down. So at the next intersection, I thought I would redline it in first gear, just to blow the excess fuel out or loosen up whatever was stuck. Well it redlined...and never came down. I shifted to second and to third and just worked the brake and clutch until I found a parking lot. The car was revving like crazy at idle, so I shut it down. I popped the hood to check if the throttle cable came off or if the 5th and 6th ports were stuck. I let the car cool for 10 minutes, but when I started it, the car revved again, so I took it directly home and got my other car. And now I'm at work, all confused.
Can someone help me troubleshoot this? I don't want to jump to any conclusions, but I think the problem is with the MAF itself or the cable connector. You see, I think I made a booboo by unplugging and replugging it yesterday while the battery was still live. I don't know what to do next. How can I diagnose this?
Also, the car really stinks now.
08-11-10, 11:19 AM
#2
What am I doing...
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hay id check the throttle body if i were you make shure you secondarys arnt stuck as well as primary flaps. also you may want to check the tps. O! and it may sound stupid but make shure your floor mat isnt bunched up and holding the peddle, i had mine do that with the same thing happening to me as your discribing, my friend almolst drove the car through a brick wall because of it. but he cluched in the car revd to redline and he shut it down, i almolst pissed my self lol (i was in the passenger seat)
08-11-10, 03:27 PM
#4
Displacement Replacement
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seeing as you were working in the general area of the OMP, I'd check to make sure the omp rod that goes to the TB isnt catchin on something or is stuck i bet you thats your problem
the omp is at the front of the engine on the passenger side,with 4 clear yellowish lines goin to the engine. when you put your stock intake back in you most likely have something rubbing against the rod
the omp is at the front of the engine on the passenger side,with 4 clear yellowish lines goin to the engine. when you put your stock intake back in you most likely have something rubbing against the rod
08-11-10, 08:01 PM
#5
Well tonight, after the engine had time to cool off, I unhooked the battery, unhooked the stock air box, unhooked the afm, checked the floor mats (clear), checked the throttle cable (attached), checked the secondaries and primaries (not stuck, moveable). It seems normal to me. So I hooked up the AFM and the battery and fired it up. It took off revving again to 3000 rpm and stayed there. When I jiggled the secondaries and primaries and throttle, it actually reved higher and slowly walked back down to 3000 rpm. Well, after two minutes of that whining, I shut her down and closed the hood.
And I searched for those four clear hoses and found them under the air pump, but I never touched them. I'm not messing with the thottle body or intake manifold. I just took out the stock air filter box and swapped in a cone filter. But when I put the stock air filter back, something went wrong. I hope it's minor. But it is not obvious...to me.
I would gladly buy another AFM if I knew that would solve the problem. If only it was that simple. Is there a sensor that could be bad, or a fuse of a sensor that may have blown? What am I looking for.
And I searched for those four clear hoses and found them under the air pump, but I never touched them. I'm not messing with the thottle body or intake manifold. I just took out the stock air filter box and swapped in a cone filter. But when I put the stock air filter back, something went wrong. I hope it's minor. But it is not obvious...to me.
I would gladly buy another AFM if I knew that would solve the problem. If only it was that simple. Is there a sensor that could be bad, or a fuse of a sensor that may have blown? What am I looking for.
08-11-10, 08:28 PM
#6
Displacement Replacement
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theres is a metal rod that goes from the oil metering pump at the bottome front of the engine to the throttle body find that and trace it from the TB back make sure its not binding anywhere
I was just mentioning the hoses on the oil metering pump as a referance to find the OMP find the metal rod that goes from there to your throttle body
if that rod is not able to move freely it will cause your throttle to stick, its a common problem.
I was just mentioning the hoses on the oil metering pump as a referance to find the OMP find the metal rod that goes from there to your throttle body
if that rod is not able to move freely it will cause your throttle to stick, its a common problem.
08-12-10, 01:47 AM
#7
Yankle My Wankel
I had something simular in my FB GSL-SE, I just redid the injector seals, and I found it it was the throttle catching on a vacuum line I had mis routed. Also take a look for vacuum leaks, but I sounds like something is catching where it shouldn't.
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08-12-10, 07:42 AM
#9
I double checked the vacuum lines, made sure everything was seated properly. Didn't find a leak. Still same problem. What is the sensor that is suppose to kick down the idle after a cold start? You know, when you first start a cold wankel, it starts off reving, but then slows down after it warms up...what's that called.
08-12-10, 07:44 AM
#10
400WHP or bust
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You have you thermal wax on the TB, and the AWS Accelerated Warm up System, I have never dealt with these as I have never had a stock car, well I guess I do now, but everything works.
08-12-10, 10:41 AM
#11
Okay, after looking this up in the FSM, I don't think my issue is caused by the thermalwax or the AWS. I thought maybe the dashpot, but that was never an issue before. And the first symptom actually occurred while I was cruising.
While crusing, it started off fine but then seemed to have a hard time maintaining 3000rpm. It suddenly sputtered a little and when I depressed the clutch and the brake to slow down for an intersection, it stalled while coasting. I pulled over and struggled slightly to start it. After that, it wouldn't idle anymore. It just revs.
Well, I'm gonna disconnect the throttle cable and cruise actuator cable, then try and start it and see what happens. This should keep the primaries and secondaries shut due to spring tension, right. There is nothing else to open the throttle body for air, so it's got no choice but to idle or flood. Right?
While crusing, it started off fine but then seemed to have a hard time maintaining 3000rpm. It suddenly sputtered a little and when I depressed the clutch and the brake to slow down for an intersection, it stalled while coasting. I pulled over and struggled slightly to start it. After that, it wouldn't idle anymore. It just revs.
Well, I'm gonna disconnect the throttle cable and cruise actuator cable, then try and start it and see what happens. This should keep the primaries and secondaries shut due to spring tension, right. There is nothing else to open the throttle body for air, so it's got no choice but to idle or flood. Right?
08-12-10, 10:56 AM
#13
AWS - the Accelerated Wear/Warmup System. But 'fraid I don't have suggestions for what you're looking for. I'd suggest a search in the 2nd gen forum.
I don't think AWS would be causing this problem, idle is too high, for too long - iirc, aws on S4 cars is supposed to run 17 seconds. You've confirmed the throttle plates aren't sticking open, but have you confirmed they are actually closing?
I remember a carb rebuild I did years ago on a Plymouth Sapporo (Mitsubishi). There were about 4 or 5 screws that adjusted hot and cold idle and the relationship between the opening of the primary and secondary throttle plates, and a dashpot and thermowax bit too. Long and the short of it, I messed up the relationships by turning screws I didn't need to (think I wanted the secondary to open sooner), started up the car, it started at 3500 rpm, dropping to 2500 after a couple minutes (got hot fast!). The throttle plates were just slightly open at hot idle - and then a little more when it was cold, and that was all it took. So close is not the same as closed, is what I'm saying.
I don't think AWS would be causing this problem, idle is too high, for too long - iirc, aws on S4 cars is supposed to run 17 seconds. You've confirmed the throttle plates aren't sticking open, but have you confirmed they are actually closing?
I remember a carb rebuild I did years ago on a Plymouth Sapporo (Mitsubishi). There were about 4 or 5 screws that adjusted hot and cold idle and the relationship between the opening of the primary and secondary throttle plates, and a dashpot and thermowax bit too. Long and the short of it, I messed up the relationships by turning screws I didn't need to (think I wanted the secondary to open sooner), started up the car, it started at 3500 rpm, dropping to 2500 after a couple minutes (got hot fast!). The throttle plates were just slightly open at hot idle - and then a little more when it was cold, and that was all it took. So close is not the same as closed, is what I'm saying.
08-12-10, 01:02 PM
#15
The AFM connector is secure. I jiggled it while the car was running and it made no difference.
I doubt it's the cold start cam, because it's idling at 3200rpm, not 1600rpm.
The FSM says don't push the throttle sensor in completely...ohoh...what if I did as a test to insure it wasn't stuck? Could that be the problem?
I doubt it's the cold start cam, because it's idling at 3200rpm, not 1600rpm.
The FSM says don't push the throttle sensor in completely...ohoh...what if I did as a test to insure it wasn't stuck? Could that be the problem?
08-12-10, 01:35 PM
#16
Displacement Replacement
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87' NA w/ 140000 miles apx.
Ok... when I start my car.. it will idle at about 1500... it will stay that way until I start driving it.
Once I start driving... the idle goes up and up and up.
By the time I made it to my buddies house last night, it was idling at 4500 rpms. It would drop down when I put it in gear and all.. but every stop light.. 4500 rpms.
First experience in my 7 with cruise control that I don't have... so I guess it wasn't all bad.
Any ideas? I was thinking the rod from my throttle down to my omp was getting stuck somewhere? Any other ideas. I did do a search and will clean it up a bit, and unplug my bac.. but really don't think that's the problem.
Fikshun
Ok... when I start my car.. it will idle at about 1500... it will stay that way until I start driving it.
Once I start driving... the idle goes up and up and up.
By the time I made it to my buddies house last night, it was idling at 4500 rpms. It would drop down when I put it in gear and all.. but every stop light.. 4500 rpms.
First experience in my 7 with cruise control that I don't have... so I guess it wasn't all bad.
Any ideas? I was thinking the rod from my throttle down to my omp was getting stuck somewhere? Any other ideas. I did do a search and will clean it up a bit, and unplug my bac.. but really don't think that's the problem.
Fikshun
go check the OMP rod it connects to the Throttle body on the opposite end of the throttle cable go make sure its not getting jammed up anywhere it happened on my buddy's TII when we put the engine in
08-12-10, 10:00 PM
#18
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disconnect anything that has to do with the Throttle body,,Like BOTH cables.
Then see if it REVS up!
I am thinking that something is preventing your Throttle body from closing.Check that too,Inside.
I have heard of a pieces of plastic from the afm going to the butterflies and holding it open.
Wierd scenario,but hey you gotta check everything,
Then see if it REVS up!
I am thinking that something is preventing your Throttle body from closing.Check that too,Inside.
I have heard of a pieces of plastic from the afm going to the butterflies and holding it open.
Wierd scenario,but hey you gotta check everything,
08-13-10, 06:07 AM
#19
disconnect anything that has to do with the Throttle body,,Like BOTH cables.
Then see if it REVS up!
I am thinking that something is preventing your Throttle body from closing.Check that too,Inside.
I have heard of a pieces of plastic from the afm going to the butterflies and holding it open.
Wierd scenario,but hey you gotta check everything,
Then see if it REVS up!
I am thinking that something is preventing your Throttle body from closing.Check that too,Inside.
I have heard of a pieces of plastic from the afm going to the butterflies and holding it open.
Wierd scenario,but hey you gotta check everything,
08-13-10, 08:02 AM
#20
I took off the air intake elbow in front of the throttle body.
The 1st Secondaries are open and the 2nd Secondaries are closed when the car is off.
When the car is started, I initially noticed the vaccum pump that connects to the 1st row of secondaries wasn't closing the valves, but after a minute it changed position and then I assumed it closed.
I'm gonna take a photo of the primary valve and show you guys something...
Maybe I'm not looking hard enough, but I'm not finding a vacuum leak.
I'm gonna have to disconnect the throttle and cruise cables just to prove they aren't the issue.
Something is tricking the injectors to squirt excessive fuel and in response suck more air. I can blimp the throttle to go way over 3000rpm, but it is not backing down below 3000 rpm.
After I run like that for 5 minutes in the driveway, I just shut her down and shake my head.
Pretty soon Aaron's gonna jump in here and say 'Cold Start Cam'. What's that mean and how do I check it?
The 1st Secondaries are open and the 2nd Secondaries are closed when the car is off.
When the car is started, I initially noticed the vaccum pump that connects to the 1st row of secondaries wasn't closing the valves, but after a minute it changed position and then I assumed it closed.
I'm gonna take a photo of the primary valve and show you guys something...
Maybe I'm not looking hard enough, but I'm not finding a vacuum leak.
I'm gonna have to disconnect the throttle and cruise cables just to prove they aren't the issue.
Something is tricking the injectors to squirt excessive fuel and in response suck more air. I can blimp the throttle to go way over 3000rpm, but it is not backing down below 3000 rpm.
After I run like that for 5 minutes in the driveway, I just shut her down and shake my head.
Pretty soon Aaron's gonna jump in here and say 'Cold Start Cam'. What's that mean and how do I check it?
08-13-10, 11:16 AM
#21
400WHP or bust
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Maybe the intake ducting has a rip in it? You did have to move it to put the CAI on; so one of the ribs might have ruprured.
Run over it with a propane torch, with the valve open, and obviously unlit, idle changes at all you have a leak, and you pin pointed it.
Run over it with a propane torch, with the valve open, and obviously unlit, idle changes at all you have a leak, and you pin pointed it.
08-13-10, 03:01 PM
#22
I don't think it's going to be a vacuum leak; un-metered air entering the intake tract would tend to lean out the mix, until it got too lean, revs dropped, and then revs would pick up again once fuel better matched air - leading to surging - wouldn't it (haven't dealt with leaks in on any car in a long time, knock on wood). So I'm still betting on something not letting the throttle plates fully close.
08-14-10, 09:17 AM
#24
Problem Half Solved...
I double checked the primary butterflies and something didn't look right. I took a flashlight and saw something. I grabbed my needle nose pliers and pulled this out. (See attachment). It is part of the old rubber gasket between the AFM and stock air box. As you can see only part of the gasket was retrieved (on the left), compared to a complete gasket (on the right). The other half must still be inside the manifold, right? (SH*T, now I have to go down and get it.)
Well, thanks everyone who said something was causing the valves/buttlerflies to stick open. It wasn't an external cable or rod. It was something from inside. I never would have guessed the gasket would pull apart and get sucked inside.