Erratic A/F Ratio under Cruise

[HLxDrummer]

yeah I meant to check the wbo2 wiring. I had a hole cut through mine once and it acted funny like yours.

There are some resistance tests in the FSM for the rear injector harness. You can do it with the plenum on.

That's good to know I would never have guessed! Ill check both of those tonight. Thank you so much!

[HLxDrummer]

Well I checked the rear injector's resistance and they all read about 3.1 ohms except the one which was like 4.4. Would this cause the car to have an A/F all over the place? The car seems to run fine most of the time, but the wideband jumps around like I mentioned.

I'm still going to try to check the wideband wiring, the resistor pack for the injectors, and possibly the O2s but it seems all the test for those in the FSM relate to wiring but they are definitely sending a signal. Dunno how long that will take though, between work and rain and snow and cold with no garage

Also, is there any way to test the ECU or knock sensor? If something happened to those plugs on the plenum it could have messed up the ECU, right? I have the ECU that came with the car but the guy did a bad job replacing the caps and I'm concerned it may blow out my sensors (when I put in the ECU after replacing the caps, the IAC magically went bad). I can just replace the knock sensor but if the problem is the ECU I would like to address that instead of throwing parts at the car. I think tonight I will run a log on my eManage and the Palm at the same time and compare the output pulse width of the Palm with the input pulse width of the eManage. I checked all the sensors on the Palm and coolant temperature/airflow/pulse width/etc. were consistent when they should be but that doesn't mean that is the actual case, right?

Any other tips? So much to check, wish I had access to a garage up here!


Edit: Just looked at the eManage log and the injector pulse width (both input and output) just varied by 0.1ms at idle and when holding higher revs with no load. However, I noticed that the ignition timing reported by the eManage varied from like 17-20 at idle (keep in mind the numerical values may be off since I never set the timing in the eManage using the base timing/timing light, but the variations should be representative). ECU? PTU? No idea.. just guessing at things that may be related to a possible coolant spill at the neck.

I also updated the first post to make things a little easier to put together.

Lastly, does anyone have a suggestion for a nice, affordable multimeter? I've been using a cheap Harbor Freight one but it doesn't even read to the tenth of a volt and has a very wide range for ohms, doesn't seem very accurate/consistent.

[DocWalt]

I would calibrate the ignition timing in eManage after you check the WB wiring, resistor pack and the O2s. Make sure your timing is reasonable then swap the possibly bad injector around and verify that the problem doesn't follow. Would you mind posting pics of your ECU boards (the one you suspect is bad)?

Are you looking for a digital or analog multimeter?

[HLxDrummer]

I would calibrate the ignition timing in eManage after you check the WB wiring, resistor pack and the O2s. Make sure your timing is reasonable then swap the possibly bad injector around and verify that the problem doesn't follow. Would you mind posting pics of your ECU boards (the one you suspect is bad)?

Are you looking for a digital or analog multimeter?

Alright ill probably check the rest of the fuses and the wideband wiring in a few minutes (the best I can without a jack).

Unfourtunately I don't have a timing light at school so I cant offset the emanate timing yet.

Do you know how to pop the resistor pack off the firewall without busting the clip?

How should I further test the o2s?

Do you know how to unplug the injector plugs? Looks like stuff wants to break lol

As far as swapping the injector, I don't know if that would help without having more widebands, would it?

Do you know what all would affect timing at idle? Like I said it fluctuates but everything else I logged is consistent so I don't know what would cause that. Maybe check it with the plug under the hood grounded?

I don't have the ECU on me but I can have my dad take a picture.

And I would prefer a digital multimeter.

Thanks a ton Kenny!

[DocWalt]

Any luck with the fuses/wb wiring?

I don't know, isn't it the same style clip that Mitsu uses everywhere?

Slide out the metal clip (if I'm wrong, you just need to pry the metal clip away from the two latches. been working on other cars with different clips and I can't remember what the 3S clip looks like) to unplug the injector. I was thinking the issue was rear bank isolated, my bad. Probably of no use to swap the injector.

Bad sensors, running really lean/rich, I think a bad air leak could contribute to it fluctuating but you pressure test all the time

Have you verified your base timing using MMCd?

[HLxDrummer]

Any luck with the fuses/wb wiring?

I don't know, isn't it the same style clip that Mitsu uses everywhere?

Slide out the metal clip (if I'm wrong, you just need to pry the metal clip away from the two latches. been working on other cars with different clips and I can't remember what the 3S clip looks like) to unplug the injector. I was thinking the issue was rear bank isolated, my bad. Probably of no use to swap the injector.

Bad sensors, running really lean/rich, I think a bad air leak could contribute to it fluctuating but you pressure test all the time

Have you verified your base timing using MMCd?

I didn't check the WB wiring yet, but all the fuses were good. Not sure how to go about checking relays...

I've never messed with those kind of connectors so I'm clueless lol I'll take a look at it sometime though, hopefully in the daylight.

I've only pressure tested once or twice but there were no bad leaks or anything and I'm getting great vacuum so I'm doubting that's a problem but when I go home I'll check that out.

I haven't looked at timing recently on MMCd but I watched it on the eManage and it was fluctuating. That was with it idling normally, not with the diagnostic thing under the hood grounded. If I ground that and it doesn't fluctuate anymore that would point to electronics, huh?

Thanks!

[DocWalt]

I assume that it would point to electronics, but I'm not sure how grounding it would relate to the emanage and the stock ECU. What happens if you disable the emanage?

[KeithMac]

Alright ill probably check the rest of the fuses and the wideband wiring in a few minutes (the best I can without a jack).

Unfourtunately I don't have a timing light at school so I cant offset the emanate timing yet.

Do you know how to pop the resistor pack off the firewall without busting the clip?

How should I further test the o2s?

Do you know how to unplug the injector plugs? Looks like stuff wants to break lol

As far as swapping the injector, I don't know if that would help without having more widebands, would it?

Do you know what all would affect timing at idle? Like I said it fluctuates but everything else I logged is consistent so I don't know what would cause that. Maybe check it with the plug under the hood grounded?

I don't have the ECU on me but I can have my dad take a picture.

And I would prefer a digital multimeter.

Thanks a ton Kenny!

The Mitsu ecu constantly alters ignition timing at idle to maintain the target rpm (700), only way to lock the timing is with the connector in the engine bay as you say.

[HLxDrummer]

I assume that it would point to electronics, but I'm not sure how grounding it would relate to the emanage and the stock ECU. What happens if you disable the emanage?

I actually unplugged the eManage and the IAC with no difference.

The Mitsu ecu constantly alters ignition timing at idle to maintain the target rpm (700), only way to lock the timing is with the connector in the engine bay as you say.

Great info, thanks! I'll definitely try that.

[KeithMac]

You need to unplug any Dataloggers so the ECU is NOT in diagnostic mode, ground the timing connector and then check the timing..

If you have the logger plugged in at the same time you`ll be in basic idle set mode, the timing will not be fixed.