E34 525i

[magno 0]

started up the car this morning no probs, pulled out the driveway and soon realised it wouldnt rev over 1500 rpm, feels like a limiter surging as soon as it hits 1500, starts & idles steady no miss or backfires, this has never happened before, i've checked over intake plugs & vacuum lines visually and with ezy start, dash says coolant level & catalytic but those have been there for months, any ideas folks?

[Mark 178]

Blocked cat converter? That's one cause of such a problem.

Heed the warnings on your dash... They're there for a reason.

[BM WORLD 1283]

yes check the cats , they block up .

have had that problem before , undo a plug bolt on the manifold to release pressure.

also is teh any fuel in the tank??

[magno 0]

plenty of gas in the tank, pulled O2 sensor from exhaust no change - just noisy, re-checked for intake leaks again - all good, pulled round plug from under Throttle Body & now it revs freely BUT idles at 1100 rpm. So, is this the TPS i've unplugged? it 's a module type box screwed to the underside of throttle body, What is the fix for this and can damage be done by driving like this? Long day, time for a beer, thanks people.

[rjac001 0]

I would check the inlet side of engine throttle is not stuck... etc

[gtirdriver 0]

plenty of gas in the tank, pulled O2 sensor from exhaust no change - just noisy, re-checked for intake leaks again - all good, pulled round plug from under Throttle Body & now it revs freely BUT idles at 1100 rpm. So, is this the TPS i've unplugged? it 's a module type box screwed to the underside of throttle body, What is the fix for this and can damage be done by driving like this? Long day, time for a beer, thanks people.

Could be your air flow meter

[magno 0]

dont think its the afm, if unplugged while running the engine cuts out, if unplugged & started engine starts & runs like normal but will not rev proper, with TPS connected the engine revs to 1500 then surges from 1500 - 2000 rpm and will not rev any higher, TPS unplugged the engine revs normal but idles high (1100rpm) and car is driveable. this has happened suddenly with no previous warning so im gonna replace suspect part this weekend & see how it goes, if anyone else out there has been through this problem - cause - solution i'd like to hear about it, could be handy for others too, cheers.

[Jo Blogs 11]

yes check the cats , they block up .

have had that problem before , undo a plug bolt on the manifold to release pressure.

also is teh any fuel in the tank??

+1 on cats, Just had this issue on my E39. Blocked cat would not rev past 1500RPM and then stalled upon throttle release.

Not to common on the 6's but mine has done 350,000KM now.