Napster134

Hi all,

So I bought some new headers and replaced my steering wheel and after these two changes my car will start for a second then just die.

Here is the story:

After installing the new headers, y-pipe, and steering wheel I was going to take the car to the exhaust shop so they could weld the y-pipe to the catback along with a new O2 bug for my EBL TT-1 WB O2 sensor. I went to start it and it started for about a second and died. I tried a few more times and each time the engine would start for just about a second then die again. I could hear the pump priming though before I try to start the engine. I started to double check things and the only thing I found is that my oil pressure gauge is pegged when the engine is off which is a new problem. I know the fuel pump uses the oil pressure switch as some sort of backup so I figure this may be related. Could someone help point me to the right direction?

Here is what I'm noticing:

1. My airbag light is on.
2. My oil pressure guage is pegged when key is ON and engine OFF.
3. My fuel pump is priming.
4. The car starts for a second then just dies.
5. TT-1 WB O2 is disconnected since I need to weld the bung on.

Here are some questions I have:

1. Does my EBL ECM use the WB O2 to add/remove fuel while engine is running? If so then do I have to connect it for engine to run? I thought it was only for tuning?
2. What would cause my oil pressure gauge to peg? From what I remember, the Oil pressure switch is used as a backup for the fuel pump relay. Could this be causing the engine to die?
3. Removing the airbag and sensors should not cause my engine not to stay running I'd expect?

Any help is appreciated!

Thank you!

Schurkey

First Guess: Spark plug wires installed incorrectly after being removed for header install. Spark plugs may have cracked porcelains.

Second Guess: Wiring to oil pressure switch is incorrect or damaged. (Perhaps wire harness has grounded wires--might kill the fuel pump as soon as the oil pressure comes up, and would drive the dash gauge to the peg.)

Third Guess: When battery was disconnected, computer lost track of all "compensation" for fuel trim, IAC, etc. Engine needs to get fired long enough to relearn.

snflupigus

5. I think this depends on if you set the EBL to run off the wideband. Check those settings first.

Napster134

Hi all!

So I ended up replacing the oil pressure sender switch. Once replaced I was able to see expected/realistic oil pressures. I’m other words, there was no oil pressure with the key on engine off. Once this was done the engine would start and stay running ONLY if I slightly held the throttle. At this point I drove over to the nearest exhaust shop and had them weld a new O2 bung for me and finish connecting the exhaust. Once the car was quieted down with the new exhaust fully connected then it ran without having to slightly hold the throttle down. I’m still curious why I had to hold the thottle down while the exhaust and wideband were disconnected. I’m wondering if it was because my ECM is using the wideband for input which I’ll double check via my calibration OR if it had something to do with the lack of back pressure due to the exhaust being disconnected from the end of the y-pipe to the muffler?

But! Those are just curious thoughts. My car is running good and I’m happy about that!

Thanks for everyone that chimmed in!

Napster134

Would ya happen to know what flag it is ?
I’d ask RBob but I feel he’s a busy guy so try to limit my queries with him and for only super critical stuff lol

midias

Many EFI cars will not run open headers if the O2 sensor is right by the exit of the pipe because the sensor sends wrong data.

Did you even have the o2 sensor connected in the first place?

Napster134

I had the narrow band connected before I took it to the exhaust shop. I was curious about weather the wideband need to be in place.

Here's a diagram:

Left: Before exhaust shop connected y-pipe to the catback. Had to slightly hold the throttle to keep the engine running at idle. Extremely loud.

Right: Once exhaust shop connected y-pipe to the catback. No throttle needed to keep the car idling. Very much quieter.

RBob

iTrader: (1)

It doesn't need to be in place.

As for the engine not wanting to idle with the open headers. It could have been due to better efficiency that caused the engine to run a little lean. The open exhaust could also have been setting off the knock sensor.

Then a lack of spark advance caused a lower engine torque. Although at a regular idle speed the ECM won't do knock retard.

RBob.