1G 1992 N/T Knock question and log

[AskaFa]

Hi, I've been having problems with my DSM lately.

About a month ago my car started acting weirdly around idle. The idle ever since I bought the car has been over/or 1000 rpms and I decided to fix that. I first deleted the FIAV (the free way method), cleaned the ISC and tested it. Idle didn't kick all the way to 1700rpms on a cold start after this fix, but it still didn't idle correctly at 750rpms.

I adjusted the BISS screw using the manual (grounding pin 10 and the plug behind the battery). But even with BISS fully screwed in, my idle was still around 900-1000rpms.

I then disassembled the whole throttle body and intake, resealed everything with new seals, O-rings and verified that there are no vacuum leaks from the intake.
After this I was able to get my car to "idle" at the designed 750rpm, but it was horrible. The car was shaking heavily and the vibrations didn't stop until i adjusted the idle back to 900.

I've been driving with my idle set to 900 for past few days and the car feels alright during acceleration, but when decelerating or cruising in gear at lower speed the car "twitches" forward and back for a few moments (I don't know how to describe it better than if you repeatedly go WOT and close the throttle immediately).

I've also checked my logs and noticed there is certain amount of Knock (sometimes even 15) which surprises me, because the ignition timing is set correctly to 5 degrees BTDC (I set this by getting the engine to TDC and reseating the Crankshaft sensor the way it is described in the DSM manual).

I've also changed my spark plugs to Iridium ones in hopes to fix this. I've used BPR7E NGKs gapped to 1mm (they don't sell BPR6E here).

The injectors have been cleaned and resealed with new O-rings, fuel pump replaced, fuel tank also cleaned, fuel filter replaced, spark plug wires replaced (NGK 8741), ignition coils replaced, the ECU capacitors changed (old ones were not leaking at all), EGR sealed and unsealed (made no difference), I even ran the car with ISC and FIAV deleted completely from the throttle body using only the BISS screw to hold idle, yet the car still idles poorly at 750 (when deleting the ISC the car also loved to stall randomly when put into neutral).

The last thing I can think of is the O2 sensor or the knock sensor somehow doing something, otherwise I'm pretty much in a blind corner right now and don't know where to continue without pulling the whole engine out.

I think that before my ownership no one really did any things to this car other than changing the oil and filters. The car was still on it's old blown out shocks and the whole engine bay even with seals, bushings etc.. looked OEM.

If anyone has any ideas, please tell me. Log is here (I used TMO) https://drive.google.com/drive/folders/1itsq9KGZ2CFFYUlCfLEkWJ8QzOYy7sq6?usp=sharing

And sorry for bad grammar, not my native language, thanks.

 

[dwb]

If you're registering knock on a N/A engine, you likely have mechanical noise like bad HLAs or maybe something like an exhaust rattle.
Looking at your log I see the idle switch isn't working. It never engages so the ECU doesn't know the throttle is closed. That will definitely contribute to idle issues. There's also a specific procedure for setting the idle stop if you messed with it.

Having access to TMO, I've converted and attached your log in CSV format so others have the opportunity to view the raw numbers.

 

[AskaFa]

If you're registering knock on a N/A engine, you likely have mechanical noise like bad HLAs or maybe something like an exhaust rattle.
Looking at your log I see the idle switch isn't working. It never engages so the ECU doesn't know the throttle is closed. That will definitely contribute to idle issues. There's also a specific procedure for setting the idle stop if you messed with it.

Having access to TMO, I've converted and attached your log in CSV format so others have the opportunity to view the raw numbers.

Hi, thanks for the reply.

I'm leaning in on the HLA problem as the lifters are quite noisy and the noise seems to slowly go away, only to come slowly back when idling, I already ordered a new set today and will be changing them ASAP. Although the lifters were noisy since I bought it, which makes it weird that it just started acting like this now.

As for the Idle switch, I did set it while checking for continuity while the throttle was closed, I set it so that when the throttle is closed it reads around 2 Ohms of resistance, and as soon as i move the the throttle it goes to no continuity. I'll recheck tomorrow if it didn't go loose and also check the wire.

 

[dwb]

The idle switch is either on or off, at least it is with 1g turbo models. It also requires that the throttle body is grounded. So, maybe you just have a bad ground and that's why you were getting 2 ohms when closed?

 

[AskaFa]

The idle switch is either on or off, at least it is with 1g turbo models. It also requires that the throttle body is grounded. So, maybe you just have a bad ground and that's why you were getting 2 ohms when closed?

I'll definitely check on this, althought I know my intake is grounded well to the body and the ground should transfer through the TB bolts, will still check tho. I've read somewhere on forums that in closed position the Idle Switch will read few Ohms while still having continuity.

 

[dwb]

Don't count on a ground through the bolts. TB gaskets are not conductive, and the TB is sandwiched between them. There should be a metal strap on top, one end held by a phillips screw and the other the TB mounting bolt.

 

[AskaFa]

Don't count on a ground through the bolts. TB gaskets are not conductive, and the TB is sandwiched between them. There should be a metal strap on top, one end held by a phillips screw and the other the TB mounting bolt.

Oh, well I definitely don't have any metal straps on the TB and never did. I'll definitely check and fix this. Thanks.

 

[dwb]

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[steve]

I don't think there is a ground screw on the NA throttle body like there is on the turbo throttle bodies. The bolts into the intake manifold make full contact with the TB so as long as the intake manifold ground strap to the firewall is in place the TB should be grounded.

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[dwb]

As usual, @steve knows what's up! I could have swore that was a NT TB I pictured, but I think it's a '90 turbo instead.
If I'm checking operation of my idle switch without a logger I use an ohm meter from the electrical blade of the unplugged idle switch to the negative battery post. Then open/close the throttle and check that you go from continuity (butterfly closed) to no continuity (open) and back (closed). If that checks out, plug it back in and see what the logger says.

 

[steve]

I could have swore that was a NT TB I pictured, but I think it's a '90 turbo instead.

That is a 90 Turbo TB. The 91-94 Turbo TB ground strap is on the TPS side of the TB and attaches to the top stud the intake manifold stay fits on. (the bracket between the CAS and the TB).

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[AskaFa]

So I checked the TB for ground today, and it is fully grounded.
I disconnected the wire from the idle switch and it still shows that the switch is in the ON position in TMO.

 

[dwb]

Check if the idle switch wire (unplugged) is showing ground. Sounds like it's shorted somewhere.

 

[AskaFa]

Check if the idle switch wire (unplugged) is showing ground. Sounds like it's shorted somewhere.

Checked that too, it does not show any continuity with ground. I went and reinstalled the idle switch, it still has continuity while throttle is closed, but now shows no Ohms.
I've rechecked the TMO and sure enough it's now working. So new lesson for me; even if the Idle Switch shows continuity and the multimeter is beeping, anything over 0 Ohms appears to still be in an "ON" position for the ECU.
I'll do another run today and log it, new HLAs should arrive tommorrow with new O2 sensor as well.

 

[AskaFa]

Alright.
I made 2 logs today. One for idling until engine was warm and radiator fans turned on and one driving around warmed up. I've also added fuel trims and some other options that I didn't log before.
The knock sensor went a little crazy today registering 36 counts at 2:24 and 2:36 in the "log03" but stayed calmer after that.
I'll definitely follow up on this thread with logs after changing the O2 and HLAs.

Also @dwb how do you convert TMO logs to CSV? I want to save some of your time by converting them myself.
Thanks.

 

[1990TSIAWDTALON]

You do have a good, functioning knock sensor, correct? No black goo oozing out?

 

[AskaFa]

You do have a good, functioning knock sensor, correct? No black goo oozing out?

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I managed to take this.
I didn't feel any leak while touching around it either.
I did not however check how much torqued it was, I've seen some threads where people had it overtorqued and it was knocking because of it.

 

[dwb]

Also @dwb how do you convert TMO logs to CSV? I want to save some of your time by converting them myself.
Thanks.

There may be a difference in software versions, I'm at 1.16.02 (1999). For me, when reviewing data, I go to File -> Export to CSV

 

[1990TSIAWDTALON]

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I managed to take this.
I didn't feel any leak while touching around it either.
I did not however check how much torqued it was, I've seen some threads where people had it overtorqued and it was knocking because of it.

That one still looks "ok". No oozing to be seen. I would assume it is functioning properly.

 

[AskaFa]

Hello again, after a long weekend working on these issues I can say that the knock sensor has no longer sees counts high as 35, but it still sees some knock.
I test drove it today after changing the lifters and the O2 sensor and the knock count went only as high as around 15. Still too much I think, I didn't have sadly any time left to loosen it and retighten with normal torque to see if that will help.
I've also tried pumping 100 octane if that would help to keep the knock sensor down, it had no effect as far as I can see.

However, the car keeps stalling randomly at stops/while cruising out of gear. I've been having this issue for over 2 months now and I thought it magically went away after some electrical connections were cleaned and the ECU caps were replaced, but it came back.

I'm thinking that it might be my MAS finally kicking the bucket, because this started happening after I changed from OEM air filter to K&N E-2875. I've also modified the aircan (VFaq guide on NT air canister modification). I've checked vacuum lines and etc.. everything reads as it should, lines hold pressure and everything is connected where the manual says it should be.

I've even tried blocking off all the TB vacuum ports and sealing them, yet the car still stalls. I'll upload some logs in TMO form to the google drive.
Thanks for help.

 

[AskaFa]

Well, again, after trying what feels to be everything, the car still stalls when put into neutral. I can say for sure that it happens about 33% of the time i put it in neutral, sometimes it holds the revs at 1000, sometimes it just stalls completely. I've also found out that my working ISC has, well... stopped working, at this point, it just basically vibrates on the same place. But since I've been having this problem for a few months now and I have a video of it working, I doubt that this is the problem.
Yesterday and today I went to remove as much of the engine wiring as possible to test it, I've tested the O2 connector, the MAS connector, the TPS and CAS. All of these reported with the Voltages that manual specifies, I've checked theirs ground as well, everything OK.
Out of frustration, I've put the car all back again as it was before this problem started occuring.
So stock Air Filter and original OEM O2 sensor.
And still the car dies sometimes.
The TPS and Idle Switch were recalibrated and are fine in the logger.
I've also tried driving with alternator disconnected, still stalls.

I would also like to ask if anyone here uses DSMlink on a N/T DSM? As I'm running out of ideas and don't really know what to do.
Thanks guys.

 

[dwb]

Well, again, after trying what feels to be everything, the car still stalls

ISC has, well... stopped working

The component that manages your idle is inop, but you choose to ignore it?

 

[1990TSIAWDTALON]

A bad ISC can burn out a component in your ECU. Don't ignore it and don't put in the "tan" colored one, get the black one. @steve pointed this out to me so I got rid of my old tan one and put a new black unit on the throttle body I was rebuilding.

 

[AskaFa]

I am not ignoring it, all I’m saying is that it worked 2 weeks ago and the car has been stalling for over 2 months now.
As I do not live in the US these cars here are rare as unicorns and on junkyards are only VAG junks, no Mitsubishis whatsoever, or old Hyundais with the same engine.
I do not want to ignore this problem, but getting the ISC will take some time, I have to contact the very few people actually driving these cars here if they don’t have parts, etc…
And to be precise, I’m pretty sure the ISC is repairable, it will just take me time, as there is not much documented about repairing them.
The coils are fine and it show some will to move, but doesn’t retract enough when cycling the ignition
I’m pretty sure the magnetic part of the ISC is out of alignment with the coils, as if you take it apart and spin it, you can see the rod moving up and down, until it reaches the limit.

 

[AskaFa]

A bad ISC can burn out a component in your ECU. Don't ignore it and don't put in the "tan" colored one, get the black one. @steve pointed this out to me so I got rid of my old tan one and put a new black unit on the throttle body I was rebuilding.

Oh, well, I’ll definitely check that, hopefully it didn’t happen.
Yes, I’ll definitely try looking for the black ones, although my choices may be limited by where I live. Thank you