fast951

Disconnect the AFM then start the car and see how it runs...

mjshira

It will fire for a moment but then dies when I disconnect the AFM..

mjshira

UPDATE:

I have Ingo's hammer (thank you Ingo you are a life saver!) and after I carefully checked and re-did all the connections to intake I ran the diag with the hammer against the car.

The hammer is telling me I have 'injector valve cly 4 open'. I put my hand on each fuel injector and the all appear to be connected to the fuel rail and connected.

So I am excited at once and now clueless....

Thoughts?

N51

"Measure the fuel pressure at the rail at idle both with the vacuum hose connected and disconnected to make sure it is in spec. If it checks out next on my list would be the injectors. Maybe one is partially clogged and can't flow enough and that throws your average mixture off under WOT. Maybe have them checked and cleaned." -Ingo


"A adjustable FPR was there for a reason. You never did check the fuel pressure before removing it. Maybe someone put it in place to band-aid a problem?" -John

James,
Can barely wait for the exciting conclusion. :-)

mjshira

The car wants to run, I think that injector once fixed will address the issue. The adjustable FPR was tired and I feel more confident having the factory part on the car.

N51

James,

Working back from the tech information and yours, brings some more thoughts. If one injector is stuck open and then an adjustable fpr is used to incorrectly compensate for the lean down on the other injectors, would it also create a washing of the cylinder wall on #4? Leakdown check?

Hope you're going to pull and check all the injectors, rather than just #4.

Too, I'd still check the before/after fuel pressure. Makes a neat confirmation to the work.

mjshira

I don't think someone used an adjustable FRP regulator, which is impossible to reach, to deal with a bad injector. I have no idea why someone would put this on the engine. All I know is I am glad it is changed. With respect to a bad injector, I just swapped the wiring between the cyl nearest to nbr 4 and 4 and cleared and re-ran the hammer test. it showed the same fault which indicates in my view that the issue is with nbr 4 fuel injector. Too bad I don't have a spare!

slammed1000

james, alot of people will use the adjustable fpr to add more fuel. with stock injectors you reach a point with stock pressure and run out of output..by adding more pressure to the injector you increase the output. if the engine does have all the parts that ebs says it did then its possible the guy added it since knowone knew how to add larger injectors and control them with motronic.i know you need you car back asap but kolb diesel service has a injector service. they are in evansville. they can clean,flow and test the inj.

mjshira

I am going to change all the injectors anyway, so removing the ones on there, getting them cleaned, putting them back on only to then remove them again is not something I think makes sense. I am going to test continuity to the fuel injector at position 4, check the injector itself, clean it and see if it then works. I've got a spare injector just in case. Once this is addressed I am going to check fuel pressure at the rail before moving on to install John's kit. I've yet to determine what the right kit is for testing fuel pressure on these cars. You would think Pelican's site would be clear on the matter but it is not.

pat056

I went to pelican parts and did a search for fuel injectors and no 964's came up, only 91-94 911 turbos. Am I missing something? Are they the same?

mjshira

They are different. Go to the 911 section, select the 89-94 range. then select c2/c4. turbos are listed near by.

I've tested the fuel injector with a meter. I can't read a signal across it, I can on the others, so its not working.

mjshira

These injectors were all really tired. I found carbon and worn seals, in general they were ready to be replaced. They had a lot of miles on them. The previous owner had the engine rebuilt but didn't do anything about the externals such as these. I am expecting the car to run much better. I am in the process of installing larger injectors and MAF kit. I will do a complete post on this when it is done.

Fast4525

The Vitesse MAF kit? What size injectors are you using? IIRC, this is a 3.8L engine you have?

Good luck with the upgrades!

mjshira

yes it is the Vitesse MAF Kit, no I don't have a 3.8, the injectors are 'larger' not sure what size, I left that to John to decide. But I can tell you that this kit is very well put together, is a lot more than just a chip that advancing timing, etc. My goal for it is to improve the drivability of my engine.

Just changing these old injectors is going to help. They were really shot!

pat056

Is ther a good DYI w/pics for changing injectors?