1998 v70 GLT

[abscate]

That cold to warm transition points to an induction leak. When cold the car runs open loop and guesses the fuel mix based on rpm. Once warm, it goes to precision metering. Any leak in the induction path will mess that up.


The revving at idle is a meaningless test. It’s under load that counts.

[454cid]

Would that cause a stumble ...no acceleration under load, .....but engine will spin to 5k rpm in neutral.

The ECU needs to know what temperature the engine it. Often times ECT sensors fail such that it always gives a cold reading, so the ECU over fuels the car and it runs poorly.

Thanks, I can change it to make sure and eliminate it as well

It would be better to get a hold of a scanner and see what the sensor is reporting, and pull any codes that would give a direction on what's going on.

[surfbug1]

Hi everyone....

Yeah my scanner port is not working.

I checked the fuse that goes to the port connection, no luck. That fuse is good, and the port still is. It working

Any ideas on the port obd port fix?

[surfbug1]

Ok update!!!!!



Just let her cool down overnight.


Did a few high speed runs on a back road

In sport or economy (switch on transmission) there was no hesitation, and it had a strong pull....up to 5500 rpms and 70 mph top speed.

(If anything, one slight mini-stumble at 3k rpms on the later runs....nothing in the total cold runs)

Temp gauge was at 3 o'clock position by the time I ended the 4 or 5 runs.

So!

Defe heat related.

Maybe this?
Coolant temp sensor...
Fuel relay...

Not this !

Vac line leak....
Intake gasket leak....
Fuel inlet clogged/fuel pump issues...


Thanks everyone! Remember my ODB port is not working, so I can't pull codes.


I'm going to check the fuel pump relay, remove it and reseat it, maybe some contacts went bad.

Any reccos on what to put on metal to metal electrical points to improve the conductivity?


Thoughts?

Big Al

[scot850]

There are things like Electrical contact cleaner. I use that and where possible a soft brass bristle brush to clean the contacts. There are also jels for wet contact electrical connectors available too.

Neil.

[surfbug1]

There are things like Electrical contact cleaner. I use that and where possible a soft brass bristle brush to clean the contacts. There are also jels for wet contact electrical connectors available too.

Neil.

Ok thanks! I will check, the auto parts stores all have different opinions.

I thought it was called dielectric grease

And whaddya think of my temp sensor theory?

I remember there are two types of temp sensors...I read that on here, will have to find that thread.

Another data point, is car will run better if I shift thru the gears even tho it's an automatic. So basically, keeping the rpms high stops the stumble...or at least prevents it.

Al

[454cid]

I thought it was called dielectric grease

Yes, dielectric grease, but it doesn't improve the contact, it prevents the contact from degrading from corrosion, by keeping moisture out. I wouldn't think you would want it on a relay, assuming the relay is in a dry environment like the interior or in a fuse box. Dielectric grease is actually an insulator.

[surfbug1]

I thought it was called dielectric grease

Yes, dielectric grease, but it doesn't improve the contact, it prevents the contact from degrading from corrosion, by keeping moisture out. I wouldn't think you would want it on a relay, assuming the relay is in a dry environment like the interior or in a fuse box. Dielectric grease is actually an insulator.

Ok thanks. So no dielectric grease (insulator)

I guess the only way ...is to just be sure the electrical contacts are clean. Then, if it's in a bad water or moisture environment, use the dielectric grease

Still working on the issue.

Funny thing is, today, car is running a little better. Still stumbles, but not as bad.

Have not done anything yet, first thing is I'm gonna remove and reinstall fuel pump relay , to make sure contacts are clean and no moisture.

Al

[surfbug1]

Okay fellas!

I took the fuel pump relay out of the circuit and jumpered these contact points as shown in this photo. #15 and # 87



attachment=0]Screenshot_20220730-185424.jpg[/attachment]


I am running it for a little bit it doesn't seem like there's a lot of improvement and. I would think that something like this would have an immediate effect so it's probably not the fuel pump relay.

[surfbug1]

Also if I'm going 40 50 60 miles an hour and I smashed the gas pedal it will downshift and go to about 4,000 RPM

But there is no power and it cycles back and forth with some power so maybe it's something to do with the turbo diaphragm or the turbo lines like one of you guys mentioned before

I'm going to try and find those and check that and see what happens next

Al