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A zone of danger.
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Discussion Starter · #1 ·
I'm gonna get into detail on this one, so cliffs are at the bottom. I dont care what you read, I just need some help!

Two nights ago I pulled the EGR outta the car due to it leaking so horrilbly that it was spraying the whole engine bay with carbon and water. So, since it was that bad, I cleaned the engine bay to make sure that was the fix and track any other leaks. The block off plates are in tight with brand new gaskets, and when the car hits open loop at 18psi, its noticably stronger. The plug toward the firewall has a resistor; the one by the cam cover is sealed/tucked away.
I washed the engine bay using Braddman's process - i.e., engine bright and CD2 detailer. I purposely went around the MAF, but it would appear it still got wet in the plug. The intake was removed, and rags stuffed in the pipe. I've done this several times before with no issue.
I pulled the car outta the garage to drive away, and the car was WAY lean, around 17-19:1 in cruise, and idled at 16-17:1 like a cammed V8. Hesitation and bucking was terrible. I thought the ECU was used to having a leak in the intake tract, so I reset the ECU and drove it. No dice. I thought maybe the 2nd EGR plug needed a resistor...nope. After I did that it ran so bad that it almost died in the middle of the road. Then it hit me..the MAF! It was running like I blew an IC hose, so I unplugged the MAF and limped it home running on the MAP sensor where it ran like a champ.
I plugged the MAF back in after letting it dry on the way home, and now the idle is fine, but still cruises at 16-18:1, constantly swinging all over the place. Open loop operation is still great, and my AFR at WOT is dead on at 11.5:1, but did need to be adjusted. I swapped MAF's with another owner, and still the same thing, so the MAF is fine...WTF!!!!???

Help...please? :(

CLIFFS:
-Removed the EGR and washed the engine bay; car idles @ 16-17:1, cruises at 17-19:1, damn near dying.
-Unplugged the MAF, ran off the MAP, and the car drives fine...pinpointing the MAF circuit as the problem.
-After the MAF/connector dryed out, car now idles fine, but still cruises at 16.0-18.0:1. Open loop operation is fine with SAFCII, but anything above idle is/was 2pts leaner.
-Swapped MAFs with another owner, but condition still exists.
 

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Removing your EGR will make your car run a bit more lean (but shouldn't be THAT lean) due to the fact that the inert recirculated exhaust gas displaces some of the incoming air (oxygen) to lower peak combustion temperatures (and thus lowering oxides of nitrogen levels), and when you remove the EGR system obviously more oxygen makes it into the combustion chamber thus leaning out the air/fuel mixture.

This may sound like a very basic question, but you did cap off the vacuum nipple on the large idle air control hose/pipe that went to the EGR VSV, correct? If not, this would cause a lean condition because air would be getting sucked in AFTER the MAF meter, thus not allowing the ECU to 'see' the extra air mass.

If that was done correctly, drive about 50-70 miles on the car without resetting the ECU so it can 're-learn' with the EGR removed, and then flash your ECU trouble codes.....do you have any? Good luck!
 

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A zone of danger.
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Discussion Starter · #3 ·
Thanks for the ideas Jeremy, but unfortunately I'm still stuck. Both the IAC hose, and the extra nipple on the back of the intake manifold are capped tightly. All other vaccuum lines in the EGR area seem secure, and no other lines were touched.

This seems to be electrical. I just drove the car again and it left the parking lot at 14.6-14.9, then jumped to 16.8 outta nowhere, and the O2 sensor was warmed up.

If its not the MAF, there's only one other possibility that *I* can think of, and thats the WB O2 plug in the rear of the engine bay. Its the only spot that has a direct, electical input on AFR in the bay.

Thoughts?
 

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A zone of danger.
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Discussion Starter · #4 ·
Hmm...found moisture in the diag port, but nothing else. The question now is, is that enough to fry an ECU?

BTW...AFAIK, I cant check the codes due to being OBDII in a pre-97 vehicle w/o updating the diag port, unless the underhood will still produce the blinking CEL (doubtful).
 

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know even though the wideband is saying lean, it could be an exhaust leak tricking the ecu to think its a lean condition. Did you experience any pinging? Also you can test the maf circut, see if there is a voltage drop across the ground circut KOEO. Good luck, maf and afr problems can be a bitch. Id try to get the obd2 port as it is a killer diagnostic tool
 

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T88 YOU
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let the computer learn for a week or so and see if the problem doesnt get better, the 2nd post is correct
 

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if it continues to stay lean for more than the ecu can correct for it will through a code. Do you still have a check engine light? The ecu will not fix itself if that light stays eliminated. It will apply a default valuve to the sensor in question and you will run in a safe mode until the problem is fixed. Unless your o2 or maf can fix themselves you should hunt which one it is down and fix the problem.
 

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A zone of danger.
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Discussion Starter · #8 ·
T34418L3one said:
if it continues to stay lean for more than the ecu can correct for it will through a code. Do you still have a check engine light? The ecu will not fix itself if that light stays eliminated. It will apply a default valuve to the sensor in question and you will run in a safe mode until the problem is fixed. Unless your o2 or maf can fix themselves you should hunt which one it is down and fix the problem.
Again, unfortunately I cant tell. There's two things I gotta do: replace my primary O2, and hook up the OBDII diag port. I have a permenent CEL due to the ECU not finding the O2 heater circuit, because my WB has its own heater and feeds a lambda signal to the ECU. I tried putting a resistor in there, but it never worked. And I can try, but I dont think I can pull the codes with OBDII by getting the blinking CEL...can I?
I'm almost positive now that the issue is electrical. The ECU isnt gonna correct itself because its getting a faulty, fluctuating signal from the MAF or somewhere else. I'm thinking of hitting all the plugs in the bay with brakeclean and 80psi from the compressor to get that oily CD2 detailer shit outta there. It may be my only option, cuz that crap is gonna hang around forever if it got in a plug.
 

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A zone of danger.
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1,175 Posts
Discussion Starter · #9 ·
Oh, and vaccuum/boost leaks are out. I can boost around 7psi and the ECU keeps getting leaner. If I had a vaccuum/boost leak, I'd be lean under vaccuum, and rich under boost. Anything above 7psi the car goes open-loop and the AFR's are fine. The only way it could be a leak and still make me lean under boost is between the turbos and MAF. Its an 18" section to check, and visibly shows no leak.

This is really starting to suck :(
 

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honestly recheck all your work i would even replace the resistor(resitors) you added just to be safe.

its always the small things .
 

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A zone of danger.
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Discussion Starter · #12 ·
Ranger498 said:
honestly recheck all your work i would even replace the resistor(resitors) you added just to be safe.

its always the small things .
Agreed. I'm gonna pull the plates and put two gaskets under each plate just for the hell of it, then cut the plug off and hard wire the resistor in. At this point I can't be to safe.
JeremyBlackwell said:
First thing is to get the diagnostics port working. OBD2 is GREAT for diagnosis. This needs to be done anyway, and could very easily show you a code for the circuit with the problem. My $0.02, good luck!
I'll get started on that. Can you still check the codes by jumping the circuits, or is the Toyota scan tool all you can use? I have a StarScan, but thats Chrysler software, so I doubt the software/files will be compatible. We'll see what happens I guess.
 

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A zone of danger.
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Discussion Starter · #13 ·
Well, I know I've posted a lot in this thread, but hopefully someone will find this in a search and the info will be useful. On a positive note, a search on MKIV.com revealed the most likely answer: I fried the O2.

http://www.mkiv.com/pipermail/mkiv/Week-of-Mon-20031117/026444.html

The quick and dirty version of that thread - someone else had the exact same symptoms, and while no final results were posted, the info was there. "...if there has been mechanical shock or the sensor has been hit with water, it can die."
Its a direct shot down to the O2 when cleaning the engine bay. :rolleyes: I'm ordering the sensor now; I'll post one last time with the results later this week.
 

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A zone of danger.
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Discussion Starter · #14 ·
New WB sensor in, and confirmed as the problem. Car cruises at 14.6-15.4:1 after an ECU reset.
Have a nice day. :D
 
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