calpatriot

That sounds like it could be your cat overheating, which would be a symptom of the engine running rich. Have you checked to see that the ECU goes into closed loop at cruise rpm?

If some fault is keeping it from going into closed loop, it will usually run rich, and the cat gets really hot...eventually it destroys the cat. The hot cat often shows up as that hot shift lever...

Is the voltage at the ECU from the water thermosensor in the range specified in the manual?

O2 voltage?

Idle mixtre adjusted per FSM?

Compression?

ramz28

how would u check the ecu for closed loop? and what if you dont have a cat?

mrpoopie

iTrader: (1)

It's really hard to get a picture, but the best way to describe it is, it plugs in right next to the check valve on the middle intake manifold, and goes into a bigger vacuum hose.


The thing is, the cat gets really hot even if the car is just sitting in the garage idling. What's strange was something that I did yesterday caused the engine and everything else to run a lot cooler. The shift lever is still a little hot to touch, but definitely not as hot as before.

The voltage at the ECU for the water thermosensor (the one behind the water pump housing with the green plug right?) is within range per the service manual.

I don't remember the O2 voltage, but when I checked it at the ECU, I am pretty sure it was in range.

There isn't a idle mixture screw on S5s correct?

I haven't checked compression, but it doesn't seem to have issues starting, does not flood, and sounds very strong.



Another update:

Here is a video of the car started when cold: video

What I find strange is it does the warm up cycle for 17 seconds, goes down to 1500, then ~ 1000 rpm, but when you look at the video, starting at 3:41, it shoots up to about 1600 rpm until about 7:07 when the engine is warm.

My question is: Is this supposed to happen?


What I did was replaced all vacuum lines, pressurize the intake for leaks, and raised the AFM a little bit.

The only areas that I could find a small vacuum leak were the areas circled in black in this picture which were basically parts of the throttle body that are screwed in such as the throttle valve lever that the throttle cable attaches to. The only other area that I found a air coming out was the triangular intake elbow.

Are those areas supposed to have air coming out of it?

I also drove the car around yesterday, and sometimes if you start the car after it's been warmed up, it doesn't idle and just dies.

Sorry for the lengthy post, and video, but it seems like I'm making some kind of progress since it will idle cold now.

RTRx7

iTrader: (2)

The only things that are abnormal are the vacuum leaks.

If you fix those, you'll more than likely fix the problem.

Try unplugging your bacv when it jumps back up to 1500 and let me know how that goes.

mrpoopie

iTrader: (1)

So those areas aren't supposed to be leaking? How would I go about getting rid of the vacuum leaks at those areas? I don't think the screws can be tightened anymore.

I'll try the BACV, in a little bit when it jumps to 1500 and let you know what happens.

mrpoopie

iTrader: (1)

Here's a video I took about an hour ago: http://s7.photobucket.com/albums/y27...5012010004.flv

So, it's having a cold start issue again as you can see. I unplugged the BACV around 1:45. The car slows down and then dies. From 2:45 to about 6:05, I am holding the gas pedal until it can idle by itself.

Also, when I was able to get the car to idle by itself hot, I unplugged the pressure sensor for kicks, and the engine did a cycling idle.

I noticed a couple strange things as well: Even when the A/C is not on, the A/C line in the engine bay is really cold. Also, I did a full fill up of gas a couple days ago, and as you can see in the video, the gauge is showing as empty.

Could one of these issues be affecting idle? I'm guessing the A/C problem probably has to do with the A/C switch.

zoomy942

iTrader: (2)

for me, my idle it was my pulsation damper leaking like crazy causing the fuel pressure to be low.

mrpoopie

iTrader: (1)

I checked the primary fuel rail, and didn't notice any leaks. Is there any other way to check and see if the pulsation damper is good or not besides fuel leaks?

zoomy942

iTrader: (2)

yes. feel it. if its working, it should be pulsing noticebly. if it is completely still - consider replacing it.

check the BAC valve too.

mrpoopie

iTrader: (1)

OK, I will check the PD. The BACV seems fine. It ohms out correctly, clicks, and raises the rpms when I turn on the A/C

zoomy942

iTrader: (2)

i thought my BAC was shot too - then i noticed the idle would drop when items were turned on, pulling load. turns out the BAC and other components were trying to compensate for the load, but the fuel leaking made it so it would just struggle

supertimbalero

I have a 90 fc vert.. When cold and I start it the idle fluctuates anywhere from 1000 to 2000rpm it's annoying.. Also my transmission?? What is the whining noise with acceleration caused by? It's almost like shattering noise..

ramz28

so ive smoked the engine again from a diff vaccum hose this time i found my major vac leak. i had a hole in my intake pipe after the MAF, i fixed it for now and my idle has changed alot, i still have to vac leaks that i just noticed they are the same as yours. but im able to hold a constant idle it does not surge anymore. but my new issue is at a cold starts its 3k then 1500 and then as it warms up it goes down to like 4-500 my lights dim and everything, would adjusting the screw on top of the intake bring that up? or the screw in the maf or the screw next to the maf? or are those mixture screws? also how can i tell if im running to lean or rich, whats the easiest way? if not im going to hook up 2 a 5gas and try and adjust it.

mrpoopie

iTrader: (1)

I would check the thermowax / fast idle cam, make sure the TPS is set properly when the engine is hot, and check for vacuum leaks.

I have sort of a whining noise as well. It's probably caused from them being old and worn. Get an audio clip of it, so we can hear what it sounds like. Have you checked and / or changed the tranny fluid? That might help.

mrpoopie

iTrader: (1)

Is the vac leak you found at the triangle elbow that goes to the throttle body? Does it matter if there is some leakage between the AFM and throttle body?

I would try adjusting the screw on top of the intake. I think if you turn it clockwise, it will bring your idle up. Remember that if you adjust that screw, you will have to readjust your TPS.

You have an S4 right? I believe the screw next to the MAF is the air fuel mixture resistor. I probably wouldn't bother messing with that unless your car is running rich or lean.

On my car, I can smell the car running rich and the exhaust fumes burning my eyes.

Anyways, here is a link to see if your car is running rich or lean: https://www.rx7club.com/showthread.p...idle+diagnosis

Also, about the smoke machine, do you have regular access to it? Would it be possible for me to drive over to you and smoke my engine to see if I can find any leaks ? I will compensate you with some beer .

supertimbalero

k next time i get a chance to record it ill try to post it... once i get it on mp4 if i have trouble il let u know.. yes i just had my clutch done (stock) and fluid changed but thats another issue cuz when i bled it, lookin a the clutch fluid reservoir theres barely any bubbles comin up when pushin in the clutch and the clutch is hard to push down so those r things im trying to get done right now also i need to replace the master clynder... ugh!!!

SirCygnus

iTrader: (1)

yes.

mrpoopie

iTrader: (1)

I tried tightening the bolts that hold the triangular elbow on and even tried RTVing between it and the throttle body, but I can't get it to seal well. Any ideas?

TheAbsence

iTrader: (19)

Did you try replacing the throttle body gasket?

mrpoopie

iTrader: (1)

No, because it's ridiculously expensive and I figured RTV + the gasket should seal it well enough but I guess not.

mrpoopie

iTrader: (1)

Update:

I got the car to pass emissions, despite the engine only having about 50 miles on it since I was able to get it somewhat running.

When braking, my idle goes down, so I might have a vacuum leak at at the brake booster.

I am still having a cold idle issue, where the car will do the cold start cycle and then just die. Beside a possible vacuum leak at the brake booster, are there any other suggestions as to why I am having a cold idle issue?

I drove the car around yesterday, and all of the sudden it went into limp home mode - as in I couldn't rev higher than 2k. I definitely smelled something burning on the way back to the house and earlier today, I got codes 8,10,11,12,18,26, and 27 which is a decent amount of sensors that the ecu uses.

From the symptoms of the car going into limp mode, and burning smell, I most likely have a bad MOP and ECU right? I tried ohming out the MOP a week or two ago, and couldn't get readings between B+ and the other two leads, but I could get a reading between the other two leads. Also, the combined resistance I got was higher than the FSM.