Problem after transmission fluid change

Post by **precopster** » 30 Mar 2013, 01:32

A couple of things if not already mentioned; condition of air cleaner element and an excessive amount of fuel pressure can achieve a rich fuel/air mixture.

As far as psi rating of the fuel system it can be checked at the fuel rail under the black throttle cover at the schraeder valve. You can use a cheap tyre pressure gauge as others have done here; pressure is pressure regardless of fluid or gas state.

Francois850 · Post by **Francois850** » 30 Mar 2013, 10:20

I did not find any intake leak, checked several times. Air filter is clean. I did check the fuel pressure at the rail and it was fine. When I replaced the oxygen sensors I did clean the connections with electrical parts cleaner.
For those who did not read everything, I remind you that when I start the car after it's been sitting a few hours, the first few accelerations are fine but soon it gets worse.

Post by **precopster** » 30 Mar 2013, 13:36

How many seconds does it take to deteriorate? 10 secs, 50secs?

The oxygen sensors don't come into play for about 30 secs. After that their readings are used to determine fuel mixture. It may be time to order a new one.

Francois850 · Post by **Francois850** » 30 Mar 2013, 13:42

They are new, not even 500 miles on them. I would say 30 seconds is a good estimate.
What if I unplugged the sensor and tried, think it would make a difference?

Post by **jblackburn** » 30 Mar 2013, 22:00

That would force the car to run in an open-loop mode where it's using "best guess" estimates for everything.

Go for it. See if it still starts running like crap in 30 seconds.

Before you do that, unplug the MAF sensor too and see if it still chokes out in that amount of time.

Francois850 · Post by **Francois850** » 30 Mar 2013, 22:13

Ok will try both, the MAF is new as well, OEM Bosch...
Thanks for your reply!

Francois850 · Post by **Francois850** » 31 Mar 2013, 19:27

So I tried with the Oxygen sensor disconnected (front one), did not feel any better, actually felt a little worse. I did not unplug the MAF because without it the car runs like hell...

Post by **precopster** » 31 Mar 2013, 20:18

I wonder if you put in the wrong O2 sensor. Which part number(s) did you purchase?

Post by **misha** » 31 Mar 2013, 20:24

I still bet on a bad transmission since the problem occured right after a fluid change or on slipping CV joints.All of the symptoms are pointing into that direction...especially the one where francois850 pushes the pedal to the floor and both RPM & SPEEDOMETER are moving BUT nothing happens(those are EXACTLY the same symptoms like with a slipping clutch on a manual transmission) .The car have NO acelleration.The same thing is happening with automatic transmission.

To make a long story short....i have a friend who had a 3 or 4 years old Grand Cherokee.He took it to a mechanic(trusted mechanic where he maintains all of it's vehicles...Mercedes CL 500,Audi S6,S8,BMW Series 5) to change all of the fluids,filters after a few days from the day he bought it.He had a perfectly functional automatic transmission and he insisted that mechanic perform a fluid change.He told him that it's not necessary and that he will do that but ONLY at his(owner's) risk.After a little persuasion,mechanic performed a fluid change.....and after about 50 miles his transmission broked and he ended up with a replacement transmission.

I'm ONLY trying to help with my advices

.Automatic transmission fluid change is very,very risky.There are a lots of members from this forum who had a perfectly functional automatic transmissions and after just one fluid change their transmissions were ruined.

To go back on the topic....for 13 years of ownership of my '97 850 i had a bad front o2 sensor(two times),also had a bad Maf sensor(2 times),bad SAS system,bad rear o2 sensor...the car was almost perfectly drivable with exeption of very HIGH fuel consumption,unstable idle and black smoke from the exhaust.So,those could not be the culprits for that power loss like francois850 have with his car,especially when he floor the gas pedal and both RPM & SPEEDOMETER are moving but nothing happens.

Misha.

Post by **erikv11** » 31 Mar 2013, 20:26

Francois850 wrote:...I did not unplug the MAF because without it the car runs like hell...

This is quite unusual. The car should struggle just a bit then the ECU goes into a default mode and the car runs smoothly. Did you unplug it first, then start it up, then give it a minute for the idle to smooth out? If so, then I wonder if there is an ECU issue, or the main issue is an AFR problem that doesn't play nice with the default AFR's.

Sure there are no vacuum leaks? (I know, you've checked a hundred times ...

)

misha, I thought OP later said the trans doesn't slip, that he was mistaken about that.

Problem after transmission fluid change

Re: Problem after transmission fluid change