Rev limiter?

nmacc

Odd problem guys,

1993 Mercedes 220TE with Bosch HFM injection (I think).

Starts, runs and is generally driveable until the revs build up. At no load she revs smoothly up to 4500 when she starts to stutter in an odd way. It's like a 4-cylinder misfire; an expert who listened to it said that it was exactly like the rev limiter kicking in.

When running on load the same problem occurs at 3500 and, once it starts, it only stops when the revs drop below 2500. It also comes in gradually at 3200 where it manifests as a rapid vibration, very like unbalanced wheels or a ridged road surface.

I've done some of the basics like changing the fuel filter, plugs, leads, etc. I haven't check compression, fuel pressure, or managed to find a spare ECU to swap yet.

Just wondering if anyone out there has come across this?

N

antodeco

Hmm, have you checked the o2/MAF sensor or air intake?

nmacc

The air intake is fine, but you're right, I do need to swap in a known good MAF. I'm going to a small local Merc garage over the next few days to beg the use of some of their spares. If I find the cause I'll post it here for posterity.

The scary bit is that another very experienced mechanic has suggested a failing head gasket. That's particularly worrying as it's only 12 months and 9,000 miles since that was done.

N