DJ,

Motor: ISC valve???

OP guage: Never seen one do that on a MKIII. Possibly the sending unit itself is hosed??

 

vac leak, tps, or isc possibly sticking. take it off, take it apart, and clean the sludge out of it. then put it all back together.

 

Bad AFM. Swap in the one from the MK2 and see. I had the same problem 5 years ago and it was a bad AFM.

 

mii afm wont work on a 7mgte

 

I'm going to take the ISC valve apart and clean it out. I'll let you guys know if that changes anything. It doesn't look all that dirty... I'm thinking it could be the AFM like Wade said. The engine was doing this before I did the motor swap. The ISC valve is the one from the JDM motor as well as the good TPS. The AFM however is the same one as before. And yes, it is plugged in. (it's easy to forget the vac line on the bottom of the intake and the connector to the AFM...)

-Dave

 

mii afm wont work on a 7mgte

talking about the 7mgte mk2 he bought from don c.

 

ah. sorry man.

 

I'm with Wade,try Agatha's AFM.Quickest and easiest to do.

 

Any luck with the oil pressure gauge problem? My mkII does the same thing now that I swapped a 7mge in it. Key on= needle pegged high, start car= slowly drop to zero. I even tried replacing the sender unit, and no luck there. Hmmm

 

talking about the 7mgte mk2 he bought from don c.

Are you sure Wade???? From DJ's 1st posting, I thought we were talking about the 89 Piggy.... Not Agatha. In which case, putting in a MKII AFM would not work. But you are partially correct. Swap in Agatha's AFM into the piggy & see what happens.

 

Are you sure Wade???? From DJ's 1st posting, I thought we were talking about the 89 Piggy.... Not Agatha. In which case, putting in a MKII AFM would not work. But you are partially correct. Swap in Agatha's AFM into the piggy & see what happens.

Chris, I'm aware he's refering to the MK3 with a lump in the idle. My Mk2 did the same thing right after the 7mgte swap back in '00. It was a bad AFM for which Don got me a new one. Those Karman Vortex AFMs can go bad if you breath on them wrong. Hit or drop it too hard, get moisture on the photostroble, mirrors or electronics in the black box and you're screwed.

I'm fully aware that flapper 5mge Mk2 AFM's don't work. I've only been into this Supra shineola since 98. I never said swap a flapper in.:wtf: I was talking about the 7mgte sitting in the Mk2 he bought from Don... :badger:

I forget he has another 5/6m Mk2.

 

I knew what Wade was saying I'll try swaping Agatha's in if the ISCV clean up doesn't do the trick... very very carefully swap it in...

-Dave

 

Just general mechanical thought here, since I don't know enough about Supras yet. Engines don't rev without air. MAF or no MAF idle usually won't change significantly simply because it can't magically pull air in around the TB (except the ISCV). That screams big vacuum leak or broken TB. Unless it is not surging that severly. Then it could be possible that the MAF is broken and lying, while the computer uses the ISCV to try to compensate for the lies it is recieving.

It's hard to be certain without being there. Is this a 100RPM surge or a 1000RPM surge. Last time I started a neon without a TB it surged continuously to about 3k and back. A broken TB blade in an SRT made it surge to a little under 2k constantly.

 

I'm pretty sure it's a sensor... not the throtel body... it's about a 1000 rpm surge from 1500 rpms to 2500 rpms constantly going back and forth.

I cleaned out the ISC valve with brake clean and it made no difference. There was a pretty good carbon build up though...

AFM is next.

-Dave

 

Check electrical to icv-Mine just did exact same thing-wire was shorting inside connector-not visually obvious-Mike

 

I had the exact same problem when my hose running from the turbo outlet to the intercooler split open in the back where I couldn't see it. It wouldn't hurt to take a mirror and peak around the back of the turbo.

-Hope it helps

 

my 7mgte swap is on progress and I have a similiar problem.

the donor was an 87 turbo that ran but was simply wrecked, I could start it just fine but it would sit there at high idle for a while, then when it got warmed up it would start to idle up then down over and over and sometimes eventually die.

Many of the hoses had cracks in them, I replaced a few but given it was going into my 85 supra I figured I could fix the problem by just replacing it all when I did the swap.

One odd thing though is I could take the ISC hose and crimp it and the car would idle down and go steady. So again, the hoses were old and I left it at that.

Well now I have the 7mgte in my supra and I am close to done but I have a high idle still, I havent ran it long enough to see if it will start to surge up and down again given I dont have the radiator in yet.

But I can again squeeze the ISC hose and the idle will drop right down, its like the ISC is stuck open and wont regulate, its just one huge vacum leak.

I adjusted the TPS per the TSRM, I can hear the ISC go click. click, click after I kill the engine like you should.

I also went to a 2JZ manifold with the 7mgte TB so I ended up using the 2JZ ISC so I dont think I would have 2 bad ISC valves ?

I dont know the exact idle speed as I just got my MSD 8920 adapter in and havent wired it yet but it sounds like about 2k.

My next steps are to see what tests I can do on the ISC valve and TPS, I hope its not my computer

 

Figured it out... sorta...

Well it fixed itself in a way... I drove it over to Lexus of Bellevue (where I work) yesterday because it was shop night so I could have the other technicians take a look at it. As I drove into the shop the idle was still surging. I got a lot of techs turned around and looking at me. I put it in a stall, turned it off, racked it, raised it a few inches in the air, and then turned the motor back on while Ian was looking at it.

When I turned it back on for Ian the surging was gone... perfectly smooth idle... I was pissed and happy at the same time! He said he hadn't touched anything and that it was probably air bubbles in the throtel body area. I guess having air bubbles messes up the ISCV. The ISCV has a coolant line passing right through it and so does the throtel body.

:weaksauce :woot:

-Dave

 

Well, that was my second guess???

At least it's running right now.

 

air bubbles messing up the ISC ? The air and coolant dont mix, dont see how that could matter or even happen.

I will post what I find.

Scott

 

The coolant just never got pushed or sucked into those spots where it needed to be. After rebuilding the JDM motor nothing had any coolant in it. It was just a mater of how long the engine needed to run before the coolant got everywhere it needed to be.

-Dave

 

any luck with the oil pressure guage problem yet? Still looking for a solution to mine.