Engine cutting out abnormally.

[Jordan]

I went for a drive today on some back roads, came up to a corner I like to haul ass into and oversteer out of. Felt a little ballsy today, so I downshifted into 2nd at about 40mph, and sidestepped the clutch (no rev match) as to compression lock the wheels and start a slide. Right as I sidestepped the clutch I hear a loud CLUNK from the rear of the car, but I was busy @ WOT dialing in the opposite lock. About half way through the turn the engine just died. I slid to a stop, thought.... WTF? and restarted the engine. Seemed fine, so I took down the straight. As I came to the next corner there were some bumps so I lifted off the throttle and started to brake. As I hit these bumps (sharp little ones) the engine was bucking, as it power was being cut on and off with the bumps. I decided to take it easy for the rest of the trip and head home.

Numerious times on the trip every time I went over sharp bumps the engine would cut out. It didn't stall, just kinda bucked. Feels like going WOT in 1st, letting off for a millisecond, then going WOT again. Anyways it only seems to do it on sharp bumps, or cornering hard on mildly bumpy road. Slow wavy bumps don't seem to effect it.

When I got home I checked the trunk, there is nothing in there to make such a loud CLUNK except the battery. I check it and it is bolted down quite tight. Took a quick peek under the car and saw nothing unusual.

Anyone have any ideas?

[randomtask37]

sounds to me like it could defintally be a diff problem. or maybe something in the bell houseing is loose and getting bounced around the clutch and such.

but thats a tough problem to analize

[Jordan]

its definately not anything like that. This is the engine cutting out, IE combustion stops happening for an instant, then resumes.

[AdamF 88iS]

Knock your fuel pump and main relays with the butt of a screw driver and see if that makes it cut.

[Jordan]

So i played around with the battery connections, they were all tight, and are now even tighter.

I got in, started the car, slammed my door shut.. engine stalled. Restarted engine, shut door, almost stalled. Repeated several times with same result.

at this point i am thinking fuel delivery, perhaps the pump under the car on the drivers side, or one of the relays.

I think i have spare relays, so i will swap them out. At least I found a way (the door) to test it without going for a drive.

It may have been my imagination, but it sounded like the engine was pinging at idle as well during the little door shutting session.

I will have to wait till tomorrow to try anything as its way too dark.

[Jordan]

alright, well i grabbed a flashlight and did some checking.

Main relay/fuel pump relay:

Banged/whacked/wiggled them. No changes with engine running.

In tank fuel pump:

Took access cover off, engine running. whacked connector, tank, everything in area. Nothing. Unplugged pump. Buzzing went away, no change in engine running condition.

Exterior fuel pump:

Definately buzzing away. Put ear up to it with engine running, and slammed door. Engine cuts and trips, but doesnt stall. Fuel pump keeps buzzing steadily all the while. Repeated several times. Results were consistant.

Checked connections on the coil, and the ground point in the engine bay. Both tight and good.

Now I am really puzzled...

[Gus]

sounds very similar to my prob....it ended up being the wiring to my TPS....it was random sometimes it worked sometimes it didnt....took me ages to diagnose it originally thought dizzy cap (although that wasnt that great either) cos it kept working fine....eventually gave up and mechanicked it..cheating i know...but yeah it sounds like a very similar problem. certainly corresponds with bumps in the road jiggling the wiring round and sending fucked up signals to the ECU.....another thing it may be could be the coolant temperature sender. check your spark plugs and see if they are flooded with fuel, that was a symptom of mine

good luck

[Jordan]

I know the TPS is good, its fairly new. The connector is on there, and seated properly.

I'm gonna wiggle every connector I can reach in the engine bay, then move under the dash and start wiggling wires. Its got to be something electrical.

[Jordan]

Fixed, it was electrical.

[DanGillan]

what was it though? for future reference...

[Jordan]

Its nothing that will ever apply to anyone else on the board, so there is no sense going into it.

[MR 325]

Was it the flux capacitor wiring?

[m42technic]

Its nothing that will ever apply to anyone else on the board, so there is no sense going into it.

Sounds like Jordan pulled a stupid. ;) :P

[DanGillan]

that doenst mean we wouldnt be interested, but ok...

[Jand3rson]

That's ok, when we were changing the oil pan on my car, and we pulled the grounding strap off the oil level sensor, the whole time we putting eveything back together, we kept saying, "don't forget that grounding strap, or the car won't start".

Of course, we forgot it, and spent 40 minutes trying to figure out why the car wouldn't start.