Hesitation and Misfire

[slvrXI]

Hey guys, just picked up a 1988 E34 with a six cylinder...

Problem just arose today, when I fully accelerate, the engine seems to hesitate quite a bit especially at higher RPMS, sometimes not even able to reach above 4k...

The problem seems to be worse when the engine is cooled off.

When sitting at idle, the idle is perfect just under 1k, and when I rev the engine, it seems to stall out at 3k and it sounds like its misfiring all across the board, then if I blip the throttle again I can get it higher but still seems like its bouncing off an imaginary rev limiter.

If I'm crusing in high gear with low RPMs (under 2.5k) and I floor it, the car smoothly accelerates, If I floor it basically in gear under that RPM it drives fine and runs great. But as soon as it reaches high engine speed it wants to die out again.

I have absolutely no idea of the previous maintenance on it and I don't want to go spending 1000 dollars on maintenace to get this car back up to perfect, I just need to accelerate with it. It has around 170k miles. What do you guys think?

Fuel filter? Spark plugs? Ignition coil?

No CEL is lit up when driving... How to check for codes without Diagnostic tool?

Thanks in advance.

-Mike

[Deanx2009]

maybe fuel pump?

[m60b30530i]

first off is it a 535i ? if so check your afm and cps . (air flow meter, crank position sensor).

[slvrXI]

I'm thinking AFM, I'll take a closer look tomorrow, but wouldn't the CEL come on for the CKP??

[ShapeShifter]

Fuel filter
plugs
dizzy cap and rotor
vacuum leaks

[Alexey535i]

Had exactly the same symptoms with my dad's m30b30. Some water came in the fuel pump, and when it freezed (winter time) the pump cracked a bit. Check the fuel pump:
1. Take off the right fuel hose under the intake manifold, put the hose in 1l bottle;
2. Jump the fuel pump relay for 20 seconds. The good pump should be working silently and should pump about 750 ml during 20sec run.
Also check (actually just change straightaway) the fuel filter.

[slvrXI]

Good deal... it seems fuel related, but the problem gets better after its warm, still has hesitation, but I can redline through 1st and 2nd no problem, just takes longer than it should to get there...

Also I noticed an MSD box sittin under the hood, WHAT THE HELL IS THAT?? Why would someone put MSD on it? and how can I make sure it is functioning properly, it has brand new wires, cap and rotor.

[slvrXI]

Bump for the MSD crap... anybody know why the hell you would put MSD on these motors?

[ILoveMPower]

Bump for the MSD crap... anybody know why the hell you would put MSD on these motors?

A picture would help! It's hard for us to know what's going on based on the description of "MSD crap," lol

[m60b30530i]

well its probably aether a blaster coil or a msd box. there really is no need for one all it does is put extra strain on the ignition system

[slvrXI]

Its MSD box, zip tied to 2 holes that were drilled in the wheel well... Rigged up basically, I don't plan on keeping the car long, I just need to get it running good for a profit sale... Paid 700 for it from my boss.

[stoney85]

I'd say firstly rule out all the basic things

so do a complete service firstly, replace ther spark plugs, fuel filter, and all other perishables, oil and filter, air filter etc

check ignition timing, and do a compression test, so then you have an indication that if nothing else is wrong the motor should run properly

then delve into the more expensive things to look at,

does your car start easily? all the time, could be a faulty ignition, not getting enough voltage, bad alternator etc

then also check fuel flow and pressure

that way you knwo the basic

[m60b30530i]

its got to be the msd box go online a check out or call turbo charging dynamics and find out how to set it up.

[slvrXI]

What about clogged catalytic converter? Would that be a reasonable explination for why it runs better when its warmer?