HELP! Weird driveability problem

[releese78]

I have a very strange problem that is making it quite unsafe to drive my car. Sometimes (usually within the first 15 minutes of driving on any given day), my car will feel like it's going to stall and eventually does. The throttle does not respond at all and it sounds like misfiring cylinders (bubbling, back-fire sound heard). The worst part is that there is no rhyme or reason and when I'm about to cross traffic, sometimes I can't go anywhere and force others to slam on their brakes as to not hit me. Usually I can tell this is going to happen because on that particular day, it will start and immediately stall. I have to rev it a few times to get going. This is somewhat rare though, usually it starts flawlessly and runs like a bat out of hell.

Since this problem has started, I have changed the fuel filter, K&N air filter, belt, plugs, and routine oil changes, and cleaned MAF. All have had no effect. There are no other engine mods other than de-snorkle (done after the problem started). The car runs at a steady 180-185 degrees, coolant bottle and cap have been changed.


The vehicle is a 98 Box, TipTronic with 102k miles. No CEL light or codes present.

Another bit of information that may or may not be related, sometimes when slowing down (entering a toll booth for instance), it seems to downshift very hard, then when accellerating out, the trans seems to have a "dead hole" and almost slip for a few seconds. I am not the original owner, and am not sure as to wether the trans fluid has ever been changed.

Any help would be greatly appreciated!!

[Lil bastard]

I think your tranny problem and rough running/stalling are unrelated.

With 102 on the clock, I would change the tranny filter and fluid - s/b done around every 45k mi. according to the tranny mfr. Same with the O² sensors - bosch rates them at 100k mi., but I've rarely seen any go that long.

As for the stalling issue, it could be so many things and anyone here can only venture a guess without actually seeing the car.

My suggestion is to get it to a dealer or indy with the appropriate diagnostic software to zero-in on the cause instead of throwing 'fixes' at it willy-nilly.

[releese78]

Will do, I appreciate the feedback. I have just put off the diag because with it being intermittent, I'm sure I'll be "going to the doctor when I have no symtoms"

[idheaton]

Although you cleaned your MAF, it may beyond cleaning and need to be replaced

I have a 99 and although it's a manual, I had some intermittent issues the one about starting out being similar to what you describe.

Some of my symptoms were:

• RPM surging at idle.
• Poor take off - Pulling out from a stop was a crap shoot. At times it just seem to want to die and I would have to feather the clutch/gas to get it going with it backfiring and when it decided to go it sometimes wanted to just take off which made me fear ending up in someones trunk. and any thoughts of jumping out into traffic were non-existent for fear of it suddenly stalling out. It was most noticeable on upward slopes where a little more gas was required. It felt like the car was either flooded out or running out of gas.
• Deadspot in the powerband - Once it was up and going, everything was fine, no hesitation or roughness except it had a tremendous dead spot at 5k rpm.

Fixes I tried were:

• Swapping out oxygen sensors
• Cleaning the ICV
• Cleaning the MAF

All of which seemed to help initially but shortly afterwards the car would go back to running poorly.

It got so bad that I was afraid to drive the car as well for fear of stalling out and I always made sure I had way more than enough room to pull onto a busy road in case it decided not to go.

I eventually had the MAF changed (as opposed to cleaning it) and all my issues went away. The strangest part of this is that as bad as the car was running it never once threw a CEL.

Goodluck with finding out what's causing your issue.

ian

[releese78]

Hmmm, sounds like a good idea. I'll change the MAF. $3-400 is definately worth the risk of getting plowed by another car!

[pk2]

Sounds kinda like fuel starvation. In that it craps after 15 minuets (about warmed up) it's no longer running rich and maybe regular lean mode is just to lean. I had this problem exactly in a BMW. Mine was always the fuel filter .

Given you've covered that base, you might take look at the fuel pump. Tests usually involve flow and pressure (2 tests).

Good luck, PK