[ansys]

My car has some engine woes that I'm just not skilled enough to troubleshoot/diagnose. Unfortunately, I don't have tons of spare time at the moment, so I'm really trying to avoid the rabbit hole of spending tons of time/money on parts I don't need in the hope that it will fix something.

Several months ago, the engine started running really rough. Kind of sounds like a tractor, low on power/poor acceleration. Engine sputters, you can see the exhaust "puffing" when this happens. Tiniest bit of smoke, can't tell if it's blue or white. Definitely not black.

• The engine was supposedly "reconditioned" about 30k km ago, so things like spark plugs should still be ok...
• I peeked inside the throttle body, and it didn't seem too terribly dirty.
• I had checked the timing when I rebuilt the distributor seals several months (or a year?) before these recent troubles.
• I used the diagnostic port and checked for any flashing codes on the dash, and it appears as normal.

- I do notice that when the engine sputters/runs rough the volt-meter on the dash drops/wiggles quite a bit. Sometimes the sputtering is constant, other times it's intermittent. When it's intermittent and I get 'normal' engine idling/running, the volt-meter needle is steady/normal. I've also noticed that if I have the interior dome light on that the light dims with the engine running rough/sputtering and the volt-meter dropping. I feel like there's a good clue in there to figure this out, but I'm a bit of a dunce

I've had this issue for months (it sits unused in the garage), and I thought I swapped out the ECU for a known working one before and it didn't make a difference, but I'm not so sure anymore. That will probably be the next thing I try and/or checking the ECU capacitors.

 

[GDII]

89-91 REV1 SW20 with GEN2 3SGE right?
The ECU might be the issue here. Like you say, try it first as they are getting older. I've not heard of a REV1 ECU failing yet but a REV2 I have so we are getting to the age where they could start. Seems mid 90s stuff failed first.

The symptoms you are seeing with the lights dimming and volt meter needle dropping is because the alternator is not charging when the engine stops putting out a signal that it's running. I'd expect what you describe to happen with the engine not running properly.

 

[ansys]

Correct, rev1 sw20 w/ gen2 3sge.
Well, I swapped the ECU with one from an MR2 that is running normally, and there was no change.
The rough engine running is significantly worse when the car is in gear. When in neutral, the engine runs smoother, almost as normal sometimes.

 

[GDII]

In gear and moving or in gear and clutch in and not moving?

 

[ansys]

it's an automatic...
so when in R, D, etc. vs. having it in Park or Neutral.

 

[ansys]

I've checked under the oil fill cap and the coolant, and neither looks bubbly or like a milk shake, so not a head gasket issue?

When the engine isn't running rough and jumping around, it seems to high idle a bit at about 1200 rpm.

I tried disconnecting the green coolant temp sensor while the engine was running cold, and the engine pretty much immediately died.

I noticed when I was in there that a metal pipe to the bottom of the IACV? is a bit loose or something. It's possible for me to wiggle it around, and I don't think I should be able to do that...
It's the pipe I drew on in red. I disconnected the sensor so you could see it better.

 

[GDII]

Oh it's auto. That's news to me!
That metal pipe shouldn't wriggle around but it won't cause any more problems than one that isn't. It's the idle valve like you said.

Maybe it's time to go 2GR? 😉

Have you actually checked the spark plugs? New plugs are cheap. If it's been sitting around and started a lot but not driven much they can foul up.
Distributor leads can cause issues when they are under load.

 

[ansys]

Believe me, I've given plenty of thought to that 2gr route lately... but with it being an automatic, I'd need to spring money on a new gearbox as well, or go the route that some people have mentioned and use the 2gr with its u660e auto box and turn it into kind of a 'sleeper' car. Unfortunately, though it's mentioned a few times, using the U660E doesn't seem to be documented at all and I'd be trail blazing with it...not sure I have that big of a project in me. I'd likely want a garage to help me out with a lot of the work, and don't know who to go with for that.

So, it's back to thinking that maybe I should just get what I have running properly again...

I was in a hurry when I did it, so I only managed to check spark plug #4 and I didn't notice anything terrible. It's on my to do list to check all 4.

 

[GDII]

You can still run an S54 which there are enough around to do that swap. This will get rid of all your auto issues.
But yes, you need to check your ignition system to make sure it is healthy.

 

[merryfrankster]

Check for a individual cylinder misfire by pulling the spark plug wires from the spark plugs one by one. If you pull a wire and the running of the engine does not change, it means that cylinder was misfiring. If you pull the wire and the running of the engine changes, then it means that the cylinder was running ok before you pulled it. Check each cylinder in turn.