Lude Generation

Well some more trouble-shooting. I figured I have the remedy for the rev dropping when halting issue, but I think this is unrelated...

Basically I started to experience persistent flat-spots on the way home from Japfest on Saturday. It did it once on the way up whilst on the motorway (It also does it on occasion on the way home from work, in the exact same place each time... Never anywhere else, so it's never concerned me before), but on the way back from Japfest it was pretty constant. It was generally when I was keeping a constant speed with my foot barely on the throttle. It would also do it when I was cruising down hills with my foot off the throttle entirely.

My car has always popped out the exhaust (when I let off the throttle or go down through the gears), but it's never effected the ride, but on the way home on Saturday, with every flat-spot the exhaust would pop and the rev needle would also flick up (and instantly drop down again).

It was doing it again this morning on the way to work. When I got to work I parked up, but left the motor running. I then gradually accelerated. All was fine until I get to around 2500rpm, then it starts to pop and splutter. Once I've past the 2500rpm zone it seems to be fine again.

When I got home I tried it again. As expected exactly the same happens... As soon as I hit 2500rpm it coughs and splutters and the needle flicks about. I thought I'd record it... Not that my description isn't spot on I tried to hold it at 2500. You can hear the exhaust popping in the background...

http://vid1332.photobucket.com/albums/w ... o5u4wo.mp4

The only things different I did the night before Japfest was I filled the tank right up (in preparation for Japfest). Normally I only fill it half way, three-quarters max. I also left the engine idling for a little while whilst I inflated the tyres (Pump plugged into the cigarette lighter). When I looked at the temp gauge it was around 130 degrees C. That's the hottest I've ever seen it, so I turned the engine off. I then started it again 15 minutes later to go home and it was around 60 degrees C.

It seems strange to me that it's only around 2500rpm and only really when it's there for a while or creep up to it. I can accelerate right through it no problem. I was thinking it was fuel related, possibly a blocked injector or dodgy FPR, but not if it's persistently just 2500rpm. Could it be the coil? I have an MSD Blaster fitted instead of the OEM coil. Worth fitting the OEM back in? Could it be any sensors? IAT? Remember I'm running an a7 with AEM EMS.

Any thoughts?

My suspicion would be the distributor (pick up or something). Or possibly the HT leads (picking up noise from somewhere?)

Phil's dodgy coil wouldn't be causing this I don't think.

I was going to suggest having a look at the distributor. Mine fell off not too long ago (me being stupid...forgot to nip the bolts up properly so they were only finger tight) and before it did fall of the Rev counter did start to jump around...but that only happened when throttling (either full or partial). And I definitely noticed a flat spot although I think it was slightly higher - around 3000-3500rpm.

EDIT: I know mines a 5g but thought it may be helpful in some way

Cheers guys. Rich has suggested replacing the dizzy as a first point of call as well...

Rich wrote:Going on what you are saying it could be a number of issues but due to the fact that your rev counter needle is bouncing at the same time as the fault occurs then the likely culprit would either be a failing ICM or a bad wiring connection to the ICM in the dizzy. It could also be early signs of one of the dizzy pickup sensors failing (CKP, CMP or TDC). My first point of call would be if you have another dizzy to try then do that so that you are eliminating all of the above in one shot.

I'm not saying that's definitely the cause but the link to the rev needle would suggest it is.

regards
Rich

Now to find one