91 Q45 cutting out but not quite stalling

[trw2k]

Ok you all have helped me out in the past with changing the chain guides, replacing the fuel pump, diagnosing and fixing and then replacing the fuel pump control unit (the FPCU that is in there now is an eBay used). I just had the spark plugs, one fuel injector and the fuel filter replaced.

Here is the problem:
It basically runs great for about 10 miles and then it cuts out. The rpm drop off like it has been turned off. I reflexively take my foot off the gas and slowly press back on the gas and it continues running great for a few seconds or a half minute and then cuts out again. It may even run great for a longer length of time but then cuts out again. It never completely stalls. Like I said it is 10 miles or so before this happens and it runs perfect until then.

The lights do not go off when this happens so I am thinking it is a fuel issue. I have searched the forum but do find anything that I think would fix it. Someone on the forum had a stalling issue and it turned out to be a transmission problem...my transmission seems to run great and it never completely stalls...

Any ideas?

Thanks!

[qship96]

check MAF sensor.

[Q451990]

Ditto on the MAF suggestion. They tend to show problems as they get hot... so your "happens after 10 minutes" observation follows. Try wiggling the connector and gently tapping the top of the MAF. It's the black box that sits on top of the hard plastic tube between your air filter cover and the rubber hose that goes to the throttle body.

Good luck!

Heath

[trw2k]

Thanks Heath and qship96...I will try that.
I cleaned it a couple months ago but it has been removed since then a couple times.

The time passing seems to indicate something warming up like you said Heath...the one clue

[goody90q45]

Thanks Heath and qship96...I will try that.......I cleaned it a couple months ago but it has been removed since then a couple times......

Also clean and tighten the pins on the connector. They should all look like the middle one in the pic.

Ok you all have helped me out in the past with changing the chain guides, replacing the fuel pump, diagnosing and fixing and then replacing the fuel pump control unit (the FPCU that is in there now is an eBay used).....The lights do not go off when this happens so I am thinking it is a fuel issue......

It sounds like you may be a bit suspicious of the Ebay FPCU so just for kicks bypass it with the engine warm and see if it still cuts out. You know your way around the fuel system so from the trunk unplug the FPCU connector and run a jumper from the pin shown in the pic to ground (i.e. the bare metal frame in front of the gas tank). If the symptoms persist (you'll know within a few minutes) go back to checking the MAF.



Where do you live? One of us might live on the next block over and have a spare MAF for you to try.

Good Luck

[trw2k]

Wow sweet thanks!

I will try tightening the connectors.

Before I replaced the FPCU I bypassed it as you described and it stalled and it also had burned connectors so I replaced it and it definitely runs better with the new used one.

I live in Seattle and I really haven't had much luck finding parts around here...the side mirror broke off so I epoxied it in a fixed position and someone recently tried to close it and broke it off again...so I need a side mirror

I will try the MAF suggestions when I get home tonight and see what happens.
Thanks!

[goody90q45]

..... and someone recently tried to close it and broke it off again...so I need a side mirror .....

What color? Which Side? There's a few members in the Seattle area. You might get some help with your MAF too.

[trw2k]

Here is a picture...it is a creme color and the mirror is on the passenger side.


I cleaned and crimped the connectors on the MAF and will drive it a while and report back.

Thanks goody90q45!

[goody90q45]

I have your mirror. I sent a pm.

[Lokim]

I live in Seattle. Maybe I can help out with your driveability problem... PM me.

[trw2k]

Thanks again Lokim and Goody90Q45.
Recently, I started working on the problem of the cutting out and stalling and I have made some progress.
I have a quick question and then I added the history below the question.

- Quick question - Should there be a ball bearing in the hose that goes from the "Y" in the vacuum to the EGR?
I found one in the short tube - see picture...

This is the history of my latest attempts to get the car to quit cutting out and stalling.

I pulled the codes and they were
12 - MAF
32 - EGR Function
34 - Knock Sensor
53 - Exhaust Gas Sensor.

I reset the ECU
- Cleaned the MAF
- Tightened all the clamps to the MAF and throttle body
- Checked all the vacuum lines and found two loose vacuum hose connections and a larger hose that had cracked and someone had taped it but there was a visable opening.
- I replaced and sealed those hoses.

The car ran great ...like a completely different car!
For the first time actually I could see why people become enthusiasts for this car.
During what became a 150 mile drive the two codes that came back were 32 and 34
I have reset the ECU and those two keep coming back.

Today I ohmed the fuel injectors and the knock sensors.
- Injectors are all in range.
- knock sensors were 550 and 100

I bought a newer but used MAF as well as two new knock sensors that I will be replacing at some point.
First though I was going to go through and clean the EGR system and tighten the electrical connection on the EGR solenoid valve.
I was checking the hoses to see how clean they were when I found the ball bearing in the hose...

Thanks!

[trw2k]

I just searched for 'ball bearing in vacuum line' and found the answer I think..some people believed blocking the smog control equipment increased performance. This guy found a ball bearing in one of his vacuum lines too....so the answer is NO..... ball bearings do not belong in vacuum lines

I am curious to see if the knock sensor code returns after I fix the EGR code.
Couldn't the EGR problem create a condition where the timing is adjusted making the car knock triggering the knock sensor code?

[Q451990]

Couldn't the EGR problem create a condition where the timing is adjusted making the car knock triggering the knock sensor code?

I don't think so. The code doesn't mean that the car is knocking - it means that the ECU isn't getting the correct resistance back from the sensor. I would go ahead and ohm test the sensors to see what you're getting...

Heath

[trw2k]

Thanks Heath...I did and one lead was 550 and one was 100...looks like I will need to change out the sensors at some point.
I have been driving it though ...it runs great and there have been no codes.
Tim