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This seems to be a good tip, thanks.

The problem is that my car does not have ISCV.
You're welcome. Sorry I mean IAC discussed above.
If I disconnect the TPS, the car will not be able to drive?
No driving needed, just test to see if idle is stable at standstill.

So, I'll check the vacuum leaks again and report back.
an engine will rev at whatever speed incoming air allows. Even with leaks, this typically cause high idle speed, but stable. Going up & down usually is some sort of idle-controller trying to catch up to leaks, but if you engine doesn't have one... wonder what's changing incoming air-flow?

Here's test, measure output-voltage of AFM. Is it steady or bouncing along with idle?
 

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Discussion Starter · #22 ·
No driving needed, just test to see if idle is stable at standstill.
No changes, whether it's connected or not.

Here's test, measure output-voltage of AFM. Is it steady or bouncing along with idle?
Measured EVERYTHING today, here are the results.
ECU voltage tests (TSRM p132):
Bat - E1: OK
+B - E1: OK (both wires - Ig Sw ON)
IG/SW - E1: OK
M-REL - E1: Wire missing
IDL - E2: OK
Vc - E2: OK
VTA - E2 (throttle closed): 5,03V (OK)
VTA - E2 (throttle open): -0,01V (OK?)
Vc - E2: OK
Vs - E2 (closed): OK
Vs - E2 (open): OK
Vs - E2 (idling): OK - stable w/ digital meter
Vs - E2 (3000rpm): OK
THA - E2: OK
THW - E2: 0,68V - cold engine. Dropped to 0,65 when warming up. OK?
STA - E1: OK
No10/20 - E1: OK
IGt - E1: FAIL (voltage too high)
ISC - E1: Wires missing

As you see, the only failure was with igniter but since my igniter is different than the US version, I'm not sure if this result is something to be worried about or not.

We also tested vacuum leaks by installing a bottle to the line and pushing smoke from e-cigarette (and compressed air) to the intake line. We found one hose that was broken but replacing that also did not change anything.
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I had an intake leak between the runners and intake plenum, under the union. Was not easy to find, but fixing that cleared my idle issues about 12 years ago. Just saying it could be anywhere.

The IGt is probably ok, as it is the IGnition 't' rigger, and since you have sparks, probably ok, unless your wobby idle is misfires.

VTA being 0 or 5V indicates you have the on/off TPS. There should be another signal from the TPS indicating TPS above 71 deg, I think. (5V when it is).
 

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Discussion Starter · #24 ·
I had an intake leak between the runners and intake plenum, under the union. Was not easy to find, but fixing that cleared my idle issues about 12 years ago. Just saying it could be anywhere.
Good point, thanks.

The IGt is probably ok, as it is the IGnition 't' rigger, and since you have sparks, probably ok, unless your wobby idle is misfires.
That's funny, now when you said it, when I rev the engine (slowly press the pedal), the engine starts to misfire. Didn't notice that before since we were just focusing on the idle.

We also removed the return line from the FPR, basically nothing comes out. Only a VERY small flow of fuel. The question is, is it the pump or the FPR then? I guess I need to investigate more.
 

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Celica Supra MK2 1983, Manual swap.
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Good point, thanks.


That's funny, now when you said it, when I rev the engine (slowly press the pedal), the engine starts to misfire. Didn't notice that before since we were just focusing on the idle.

We also removed the return line from the FPR, basically nothing comes out. Only a VERY small flow of fuel. The question is, is it the pump or the FPR then? I guess I need to investigate more.
Could you take a video of it, so we can hear it ?

Note: I'm a Mk2 beginner, so take with a grain of salt.
When i was working on my car the CEL also lit up and it almost wouldn't start, when it did it ran terribly; If i pressed the pedal fast to the floor it would almost die, and then increase RPM a tiny bit while what sounded like misfiring. It turned out i had bumped one of the 2 sensors (do not remember the name) in the thermostat housing, when i plugged it in again it went back to normal. Just a story, as i said, i have no idea what i'm doing.
 

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Discussion Starter · #26 ·
It turned out i had bumped one of the 2 sensors (do not remember the name) in the thermostat housing, when i plugged it in again it went back to normal. Just a story, as i said, i have no idea what i'm doing.
There are 2 sensors, one is for engine water temperature and another is Cold Start Injector time switch. Both seem to for in my car, they were measured separately (resistance values from TSRM) but also from the ECU pins.

I have a couple of videos about the idle problem, I'll post them to a separate album. Hope it helps.
 

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I re-read your posts and I did not see you mention it, but did you check the Ignition timing?
If the ignition is way off you could get backfiring and rough idle.
It's pretty fundamental, but I tend to forget the fundamentals...
 

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Discussion Starter · #28 ·
I re-read your posts and I did not see you mention it, but did you check the Ignition timing?
If the ignition is way off you could get backfiring and rough idle.
It's pretty fundamental, but I tend to forget the fundamentals...
It's good to focus on fundamentals also - especially when I did not remember to mention everything.

Since I replaced the cam tower gaskets, I had to remove the belt and after that I naturally re-checked the timing. Also, the problem already existed before that also so nothing changed while adjusting the timing.

Once again, I really appreciate the time you guys use to help me with this problem.

BTW, I just received a fuel pressure meter so measuring the fuel pressure from the CSI my next step. I also found a replacement ECU from eBay and it should be here soon so at least we have some additional information if no root cause is found.
 

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In our markets, the idle device is at the end of this tube. Might be the case at your location too. As for the TPS, does not hurt to try disconnected.
View attachment 20334
Jocelyn brought up a very good question. What is on the right side of this hose? Could you take a picture of it?
This hose and whatever is attached to it is used to adjust idle speed.

For the 1982 model, the TSRM goes so far as to have one squeeze this hose shut to see the effect on idle speed.

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These pictures are from the attached section from a North American Market 1982 TSRM.
The electrical connection is just 12V and ground to apply heat to a bimetal strip which causes the valve to close as the strip heats up.

The check in step 1 really does work. When you pinch this line shut, the engine will actually stall.

Dale
 

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Discussion Starter · #30 ·
The check in step 1 really does work. When you pinch this line shut, the engine will actually stall.
Wow, thanks. I don't think I have ever seen that old TSRM before. I'll test it as soon as I get the new fuel pump installed with a new fuel pressure regulator.

What also happened before this was that I checked the fuel pressure from the CSI line. Slightly less than 1,5bar, which is way below the limits in the TSRM. That's why I decided to go for a new pump and regulator (just in case). Of course I'll also replace the fuel filter.
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I was afraid that the filter next to the pump might be full of old gasoline remains and rust but surprisingly it was all good.
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Discussion Starter · #31 ·
Turned the engine on today with a new fuel pump. Idle was slightly better than before so I started to think about the pressure regulator anyway. Also the CEL was still on. After a short moment I realized I still had not tried the other ECU I bought from eBay. Replaced the original with a new one and turned the key - damn, it works! No more CEL, no more wobby idling.

The only minor issue still remains; the can tower still leaks oil over the exhaust manifold but now I just need to open it again and apply some gasket maker to seal it properly.

I really appreciate your efforts, I know how frustrating it is to diagnose a car over the internet but I had plenty of good advice and tried to check those all. Thank you team!

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When i had the head done may years ago (10+) i had the machine shop coat the metal cam tower gaskets on boths sides with a thin coating of Permatex Ultragray (82194). Worked like a charm and remains leak free today (wish I could say that for the rest of the engine...)

hth

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Discussion Starter · #34 ·
When i had the head done may years ago (10+) i had the machine shop coat the metal cam tower gaskets on boths sides with a thin coating of Permatex Ultragray (82194). Worked like a charm and remains leak free today (wish I could say that for the rest of the engine...)
Sounds good. I tried "Wurth Super RTV silicone plus" yesterday. I also found out why it was leaking: The Felpro gasket is a little bit too wide in the area marked in the picture and the gasket was bent there. I used Dremel tool to snap a little bit off the gasket and added sealant to the whole gasket on both sides. Let's hope it works now. Planning to start the engine today.
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Discussion Starter · #35 ·
Drove her out of the garage today. No leaks, engine runs great. Sun is shining. What else can I ask :cool:

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