M44 startup issue

[muggler]

Hi all, this is my first post here. I've been lurking for a few months and gleaned a lot of useful info. Now I've got a question:

2 days ago my wife's 98 ti started losing power intermittently while driving, stalled at a stop light, resisted starting, but it made it home to the garage.

Now it will start very rarely and stalls after a few minutes of idling.

I installed a new cam position sensor about a month ago due to a p0340 code, but the code came right back.

I have spark but no fuel. But the relays test good and so does the fuel pump. If I jumper things, I get 43psi on the rail. However, even jumpered, the car won't start.

I've searched through old threads and my best guess at this point is the crank sensor. Bentley says I should read 1280 ohms across terminals 1 & 2. I haven't taken the manifold off yet to get to the connector, but at the ECM (which is bone dry, by the way), I'm reading 580 ohms across the crankshaft sensor pins. One other thing. Pin 71 is "ground for analog signals and knock sensors," but there is no continuity to ground there. Otherwise the harness seems to check out OK.

Update:
For the heck of it, I pulled the ICV connector. The engine starts right up--but idles around 600 and is rough. Guess it's time to clean the ICV and see what happens.

Ideas/advice would be much appreciated.

[dave45056]

Help me understand your problem...
Your Fuel pump tests ok.
Your fuel pump relay tests ok
But you have no fuel pressure unless you jumper the Fuel Pump Relay?

Disconnecting the ICV allowed the car to start? was the Fuel Pump Relay jumpered then, too?
Have you tried disconnecting the MAF and starting the car? (I'm curious if you wrote ICV but meant MAF).

Did you ring out the wiring between the Cam position sensor and the ECM? Does the new Cam position sensor test out OK according to the Bentley?

[xxxJohnBoyxxx]

Originally Posted by muggler

Hi all, this is my first post here. I've been lurking for a few months and gleaned a lot of useful info. Now I've got a question:

2 days ago my wife's 98 ti started losing power intermittently while driving, stalled at a stop light, resisted starting, but it made it home to the garage.

Now it will start very rarely and stalls after a few minutes of idling.

I installed a new cam position sensor about a month ago due to a p0340 code, but the code came right back.

I have spark but no fuel. But the relays test good and so does the fuel pump. If I jumper things, I get 43psi on the rail. However, even jumpered, the car won't start.

I've searched through old threads and my best guess at this point is the crank sensor. Bentley says I should read 1280 ohms across terminals 1 & 2. I haven't taken the manifold off yet to get to the connector, but at the ECM (which is bone dry, by the way), I'm reading 580 ohms across the crankshaft sensor pins. One other thing. Pin 71 is "ground for analog signals and knock sensors," but there is no continuity to ground there. Otherwise the harness seems to check out OK.

Update:
For the heck of it, I pulled the ICV connector. The engine starts right up--but idles around 600 and is rough. Guess it's time to clean the ICV and see what happens.

Ideas/advice would be much appreciated.

If you have fuel pressure and spark and no fire then I would check to ensure the injectors are firing. They need 12 volts when key is on and the ground is what makes them fire. Are the plugs wet?

[muggler]

Thanks for the responses. Sorry to reply after such a long interval. I think I've got the problem solved, and I want to update this to maybe be of help to others in the future. After testing all kinds of complicated stuff, I went back to basics. Turns out that although I had spark, it was mostly quite weak. Insulators on 2 plugs looked cooked--no doubt due to oil from my valve cover gasket leak. So, I put in 4 new plugs and it started right up and ran fine. I had replaced the gasket and all that not long ago, but some of the threads were stripped. Guess it's tap and die time.