C4Scott

Just really straiting to get my hands dirty on some minor stuff as first time 928 owner going back to last September.

Yesterday had a tough time getting the engine to catch after attempting to start the car. Plenty of start power no response. I modulate the pedal and eventually it catches. It's getting worse each time.

Once it turns over it idles rough for a few seconds, almost stalls, and then runs fine even at lights.

Initial fuel pressure is obviously an issue but besides the fuel pump what else might be happening or rather where else should I look?

All I can find asother potential culprits are:

Mass Airflow sensor
fuel pump relay

Other ideas?

jcorenman

Scott,

I does sound like fuel, or a fuel-related problem. I would start by checking fuel pressure, Roger sells a gauge kit which attaches to the fitting at the front of the pass-side fuel rail for testing. With the fuel-pump relay jumpered you should see 55 psi (3.8 bar) with engine off, or with engine running somewhere between around 48-70 psi depending on engine vacuum (55 with the vacuum line to the regulator disconnected).

The MAF is a likely culprit, the best way to diagnose that is to borrow a known good one locally, if you can.

It could also be the Temp-II sensor (on the water bridge, at the front of the engine). It should measure about 2000 ohms (depending on temperature) from either terminal to ground. This sensor has two resistance elements, one for the LH and one for the EZK (with separate terminals), and is grounded via the water bridge. A better test is to disconnect the battery, remove the big LH connector, and check the resistance from the LH connector-- this will check the harness also. This is detailed in the WSM, in the troubleshooting section for the LH.

yardpro

if motor is dragging look at TBF

docmirror

If the engine turns slowly on cranking: Large ground cable between engine and chassis. It can look good and still have high resistance. Main power cable from batt to starter. This can also affect the the LH.

SteveG

Engine cold, it's prob not the TBearing, but if an a/t this should be checked anyway. Did you put a meter on the jump start post? Then at the batt. These cars eat batteries unless you had it unhooked or had maintainer on it.

Next thing I'd check is the Temp II, since it is up front and easily done.

jcorenman

We need the OP to clarify... I read this to mean that it cranks OK but doesn't light off right away... which sounds like fuel. But that may be all wrong.

C4Scott

Jim is right. I think it is bad gas. It cranks fine but just takes a long time to catch but once it does it compensates eventually.

It really struggles to get balanced. I force the rpms up to about 3000 just to make sure it does not stall and then it pegs up to about 1500 and drops and then settles in at the right levels after about 20 seconds.

Knock on wood but Ive never had a tank of bad gas that I have known of anyway. I filled it with 93 Shell an added some octane boost anyway to see if it would remedy the situation. Unfortunately it was a Shell station I never use that I may have received the bad gas from in th first place .

Calgary Ole

Check the fuel pressure regulator and the two fuel dampners for leaking first. Pull the vacuum hose off each one and smell for gas as they will leak into the vacuum system.

When one or more leaks, you can get the symptons you describe. Also black sooty exhaust for the few moments after it starts.

C4Scott

I did have the smoke this morning when the engine was the cold. Maybe its not the gas.. great...

Bill Ball

+1. You need to be clear in the description or it can mislead people into thinking you have other issues, like TBF, which I don't read as your issue at all. Slow to turn over can mean slow cranking speed to a lot of people. But it seems like this has been clarified now. Ole gave you some higher likelihood things to look at.

17prospective buyer

Guys couldn't it be his crank position sensor/wiring harness? A crank position sensor usually thinks the motor is running at anywhere above 400RPM, IE, when a certain RPM is hit, it basically tells the ignition system and fuel system through the computers to start igniting/injecting at an open loop variable A/F ratio. But, it tries to maintain a cold start/cold idle open loop A/F based on several other inputs like intake air temp, air mass, barometric pressure (at Key On Engine Off position), air pressure.

JHowell37

Putting in 93 octane and octane boost on top of that can drastically curb your performance. It may not cause the problems you're having, but it won't help them.

pjg

This car sat for years thus the low mileage, I suspect its a fuel issue, if not already done I would replace the fuel filter pull the injectors and have them tested and cleaned. The screens on the injectors get full of crap over time.

Bill Ball

The CPS either works or nothing. I haven't heard of the complex failure mode you are suggesting.

blown 87

I don't.
One thing is certain and that is taking folks guesses as to what is wrong and not testing is seldom a good plan on a problem like this when most of us are not real sure what the symptoms are exactly.