Totally stumped

[gusu]

So I've been having a issue where my idle is perfect then randomly drops maybe 150 RPMs and goes from a perfect 14.7 open loop and spokes to 12.9-13ish. While cruising around 1.5k (like 30 MPH in 4th to save gas) it does the same thing.

Under engine braking the idle seems to drop the same and the fuel either goes a bit more rich or a bit lean then bucks.

Today I noticed when doing a quick little 2nd gear pull to get up to 55 on the highway real quick my AFR was 15.9! However partial throttle pulls (like 60%) are around where they should be. I hit the 15 PSI I have been normally hitting and was not creeping or anything. I also have not noticed any difference in spool up time.

The other day I opened my hood and noticed my manifold was glowing slightly, although it was night and I had been driving for about 20 minutes. I did give my car 45 seconds to cool down like I always do, and I was not in boost at all during the time I was driving home from work.

I should also mention last week I hadn't really been having any problems with AFRs outside of the drop in idle so I thought maybe the fuel wasn't burning correctly because of bad spark plugs. So I replaced them with the proper BPR6ES spark plugs and gaped them to the proper .28 the manual calls for. I also checked the cap on the old plugs and they were all the way out to .40WTF, I should also mention the spark plugs even properly gaped made no difference at all. The old plugs were a light brown, most likely because of the previous owner using a octane booster or some BS like that. Nothing out of the ordinary, besides the gap.

I am also having a warm start problem where the idle does the same thing but way more extreme, it smooths out and goes back to normal after 20-30 seconds of driving.

My car also died after letting it idle for about 30 seconds after driving home from work today, it was so freakin random. It was doing it's typical 150 RPM drop then randomly it totally died out of nowhere. Just as fast as it typically would raise the idle it died, almost like it didn't even attempt to raise the idle.

I've been thinking this could possibly be a bad fuel pump or a bad fuel pressure regulator. Everything I look up does not really fit my issues.

If you read everything... kudos.

 

[H@xtGSX]

I agree. The FPR and pump is what I would check out... Sounds like a fuel delivery issue. Too inconsistant.

 

[racer009]

do you have the bov releasing into the atmoshere? my car was doing about the same thing with the idle when i had it releasing into the atmosphere. after a high rpm run and pushing in the clutch, my car would just die. it would even stall out idling in the driveway as well. once i put the hose back on the bov to the intake those problems stopped.

 

[H@xtGSX]

The BOV wouldn't cause the AFR to spike like that under accelleration. That is likely caused by a real low fuel pressure dip at high demand, because ether the pump can't keep pace or the fpr is blown out and not doing anything. Pumps have more stuff that can potentially fail in them, so that would be my first suspect.

 

[92mitsubishi]

i would have to go with fuel pressure regulator

 

[gofer]

I've realized in the 6 years I;ve been doing this is that its really really easy to start shotgun troubleshooting, seems that in the end all you end up doing is replacing a lot of parts that weren't broke, you've got a bank account thats got a few less $$$ in it, and the car is still doing the same thing.

That being said, have you checked your cars base timing yet?
1g How to set base timing WITHOUT using a lower timing cover

 

[gusu]

I've realized in the 6 years I;ve been doing this is that its really really easy to start shotgun troubleshooting, seems that in the end all you end up doing is replacing a lot of parts that weren't broke, you've got a bank account thats got a few less $$$ in it, and the car is still doing the same thing.

That being said, have you checked your cars base timing yet?
1g How to set base timing WITHOUT using a lower timing cover

Good call on timing, I didn't even really think about that. But my spark plugs were at their 45,000 mile mark so I replaced them anyway.

I listened for boost leaks and I did find a tiny hissing sound coming from the blow off valve area. I still have stock rubber piping so I'm going to tighten everything down and see if I can still hear it then take it out for a test drive. I'm hoping it's just something stupid like that.

I'm just hoping that the hissing isn't that my BOV finally took a crap, and yes I still have the stock 1g BOV and it is indeed recirculated.



*edit* Found a boost leak at one of the BOV lines, just went and tightened them all up now that one is gone. Also one at the throttle body, the car was still kind of warm and didn't really show any signs of the same problem. I'm hoping it fixed it, although I'm sure it's something else.


*Yet another edit* The spike during idle and same RPM sustained driving seems to be gone, I am still having the same warm start issue though.

 

[gusu]

Just an update, today I drove for about 15 minutes and the car ran great and had no issues at all. Although at start up it was at 15.3-15.7 for about 20 seconds until it finally hit open loop. It smelled like fuel for a bit although it was right at the correct mixture the entire rest of the time I drove.

 

[gofer]

Did you check base timing?

The car should be idling/cruising in closed loop, not open loop. Is the front o2 cycling around .5v and what do your logged coolant temps look like?

 

[gusu]

Did you check base timing?

The car should be idling/cruising in closed loop, not open loop. Is the front o2 cycling around .5v and what do your logged coolant temps look like?

yeah, I realized I had been calling it the wrong thing after I came back to check up on my thread.

I have figured out how to find everything with my logger except coolant temps.

However, I did notice today that when my GF and I went out to lunch and came back I was getting zero fuel and never heard the fuel pump turning on.

So, I was already looking at upgrading my fuel system with evo injectors and a Walbro 190 pump, and getting some sort of cheap SAFC for the time being.

Anyway, do you know if the extreme PSI install kits are rewired or if they are just a new harness?

 

[gofer]

If you're talking about the Walbro install kits then no, they don't come with the fuel pump rewire kit. STM sells a good FP rewire kit for a reasonable price.

 

[92awddsm]

I gotta ask... have you pulled the ecu and checked for leaking caps yet?

 

[gusu]

I gotta ask... have you pulled the ecu and checked for leaking caps yet?

Sorry, I took so long to reply. I did check and nope, there is no residue or leaking caps.

So tonight I looked up the range for resistance on the wires. All the wires tested fine except the number 1 wire either gave no reading or if I moved around some it would give wacky ass readings like 17000-66000. When I would put it back in place and test it to kind of simulate how it would be in the car it gave a off number but it was only around 8000-9000 ohms.

I think it is safe to say there is a break somewhere in the wires. Either way they have somewhere around 40,000 miles on them. I'm just going to replace them and see if that fixes some of the problems I've been having. I've also noticed my AFRs are more normal now. I'm probably going to upgrade to a wally 190 as I have been wanting to for quite some time now and haven't gotten around to actually doing it.

I'll post the results.

 

[gusu]

So, I've been waiting a few days after changing plug wires to see if there was any change.

So far I have noticed the fuel is more stable and there isn't a random stutter. The only thing I can't confirm yet is if there is a issue starting while warm, I've only done it a couple times and it SEEMS fine but that really means nothing since it didn't do it every time before.

 

[dsmsleeeper]

As stated above check you ecu for cap leakage. Try replacing your fuel filter along with the wires its part of your maintance. Might not need to spend the cash on a wally.

 

[gusu]

The fuel filter is pretty new, just replaced the wires as my last post stated as well as plugs shortly before hand.

When I went to repair my logging cable I removed the ECU and didn't see any damage, plus leaking caps smell terrible and with my car being a DD I'd imagine it get smelling foul after a short amount of time.

Anyway, I just wanted to confirm my car runs GREAT aside from the start up issue now. When it's warm it just wants to act like it's not getting enough fuel. I have read the only two things that cause this are a thermo sensor or a bad fuel pump.

I've checked a lot of posts and can't really seem to find any useful information. I just want to know which sensor it is it would cause this? I know there are three thermo sensors on our cars and I've seen the picture with where each one is located and which is which. I just need to know which one would be likely to cause this, I know one is for the ECU and one is for the gauge, and I can't remember what the other one was for. My guess is the one that sends to the ECU is the one that would be sending a bad signal?

All of my sensors look like the original ones and look like they have never been replaced. I may just replace them all if they aren't that expensive. I just don't see any point in letting them fail later when I could just replace them now and avoid another diagnostic problem.

By the way, I did test my O2 sensor with a propane torch at work. It heated up to .9 volts in about 12 seconds and with in a quarter of a second or so it was reading around .008-.009 or so. From everything I have read that is exactly what a good one should do.

 

[gusu]

I did replace the coolant temperature sensor and it didn't fix the problem... kinda was expecting that but it was cheap and easy and I don't mind replacing ancient sensors.