where to look first

[pyrie]

problem:
- difficulty starting (especially after a few days of not driving)
- when started: rough idle
- when revving in neutral: no smooth climb in RPM (like he has the hiccups)
sometimes the RPM gets stuck on 3000 and after a second, he continues climbing
- when driving in low RPM (1000-1500): impossible to accelerate. car hesitates
- when accelerating: 1500 to 2500 RPM: no problem, then at +/- 3000 it hesitates and then above 3500 it continues climbing.

Where to look first?
- spark plugs?
- fuel pump?
- injectors?
- valves?
- other?

Grts
Pieter

[shogun]

Pieter, more details please. That is not enough: 1989 e32
735, 730 with M30, automatic yes/no, if M30: with EML or not? Or a 750 with M70?

Basically all the items to be checked are here https://www.bimmerforums.com/forum/s...power+ultimate

[pyrie]

oh yeah, sorry

it's an 730i M30 manual with EML

[shogun]

I would first check for air leaks, especially on the M30 there are a lot of vacuum hoses, also under the intake. Start the cold engine and spray starter pilot around (not in) intake and all the hoses, if the RPM changes, you have a air/vacuum leak.
http://www.nmia.com/~dgnrg/hose_map.jpg
https://www.bimmerforums.com/forum/s...ghlight=intake

[pyrie]

Hi,

I didn't find any air/vacuum leaks, so step one I think is OK.

Next I tried to check the spark plugs, maybe there's a different color in one or two spark plugs.
But I didn't get a chance to look because I can't unscrew the spark plugs. They don't move an inch, even my good friend WD40 didn't help

Before I continue: is it oké that I put my full weight on them to unscrew, or is there an other solution?

[pyrie]

So,
I managed to loosen the spark plugs.
They seemed fine to me (color wise)
But the distance where te spark 'jumps' was more than a millimeter (way too much I guess) so I took my hamer and smashed it to 0.6 millimeter.

Result: smooth idle, no hesitations while revving (for now).