Contour Enthusiasts Group Archives Forums General Troubleshooting CEL codes, stalling, trouble shooting

Well my check engine light has been on for a while and I am wondering where to start. Here�s the info.

Check engine lights been on for a while. The cars stalls some times when started, its starts up and reaches about 1500-2000 rpms and then drop to 0, will do this 2-3 times in a row on occasion. Happens randomly sometimes not for a week or so, maybe more frequently in the cold?.

Stalling during left turns usually braking into left turns, even with close to full tank of gas.

Hesitation at low rpms, happens occasionally usually while engine is cold.

Went to AutoZone today and that the check engine light check/scanned. Here are the results

P0133-Upstream Heated Oxygen Sensor circuit Slow Response - Bank No. 1.
P0153-Upstream Heated Oxygen Sensor circuit Slow Response - Bank No. 2.

P0401-Insufficient EGR Flow.
P1151-Lack of Upstream Heated Oxygen Sensor Switch - Sensor Indicates Lean - Bank No. 2.

Where do I start, the car probably need some scheduled maintenance. Here�s my list.
Spark plugs
Fuel filter

So what�s next, from what I have read, and I have read a lot on these forums already 8 hours worth I would say.

IAC
PCV
EGR
EGR-cleaning
Vacuum leak
Intake (upper/lower) systems rebuild
Fuel filter
Fuel pump
MAF
Spark plugs

So please give me some input and where to start!!!

1997 Mercury Mystique
107000 miles
V6 2.5L


Thanks Andy

I had some of the same problems you are having. My car would stall during left hand turns as well. Mostly when the gas tank was near empty, but it did it a few times while nearly full. I cleaned the throttle body and IAC. I replaced the EGR valve, fuel filter, air filter and DPFE. I still have a cell on, I believe it is one of my O2 sensors on bank 2. Hope this helps.

Andy,

Welcome to the forum!

From your post, I'd suggest three likely courses of action:

1: Replace both upstream O2 sensors

2. Clean or replace the IAC valve

3. Service/repair the EGR system. Most common faults are either clogged TB passages or a faulty DPFE sensor.

Reset computer when done to force it to relearn everything.

The spark plugs and fuel filter replacement are also well recommended.

Once those are all done, see how the car runs and decide if any issues remain that need attention.


Steve

Good troubleshooting plan on the above post; the upstream HEGOs are probably shot. Most likely the EGR valve is fine, but the EGR passages in the upper intake could very well be clogged, as the previous poster said. It may be a good idea to replace the DPFE module as well, because you'll have good access while the upper intake is off, and they're cheap. But when they go bad you usually get a P0402, or excessive flow. Still, not a bad idea at this time. Don't worry about your MAF right now, it's expensive and there's no indication it's bad. The IAC could be sticking, which can happen without setting a code, but again, save replacing that until you do all the first order items already mentioned. Don't forget to get replacement gaskets when you pull the upper intake.

OK, thanks for the input guys.

Is this correct,DPFE= Differential Pressure Feedback EGR

I am having a hard time figuring out where everything is located on the engine. Is the following correct?

The EGR is back right and looks like a 3in sauser

DPFE is under the EGR

IAC valve is behind the EGR and looks just a little bigger than a roll of film, laying horizontaily.

Not sure what or where the pcv valve is?

O2 sensors
Bank 1, sen one is located here(first upstream sensor?)
Where is the other upstream sensor?
(basically where are the two upstream sensors?)

Thanks Andy

Does anyone have a picture of this stuff

Where are the two up stream O2 sensors located?

I just want to make sure I am changing the right ones?
How do I ask Autozone for them? I don't know if they will know what ones the two upstream ones are?

Thanks Andy

Wow, I don't think I could have gotten two better posts than that. Thanks a lot Chongo and Project

Andy

Ok cleaned the TB, IAC and MAF. Replaced PVC. The TB needed a cleaning badly.

Reset the computer drove and CEL returend broght it back to Autozone and scanned again.(after 60 miles)

Only one error now P1151, So I picked up 1 new O2 sensor. Where do I put this bad boy, bank 1 or 2(rad or firewall side)?

I know it was suggested to replace both O2 sensors but I don't really have the 120$ to drop into my car right now. But I WILL if you guys think I should!

Thanks Andy