Severe hesitation problem

[BongC36]

My 95 C36 has developed a new malady: When I floor the throttle from cruise the RPM will increase gradually then pause at a certain point for 2 full seconds then zoom up then pause again at a higher level for about 2 seconds then zoom up again! Weird to say the least.

I have already changed the wiring harness before, new MAS 2 months ago, new plugs, 2 new coil packs.

I did a search of course but none of our previous posters describe a condition similar to my cars' malady except the post by Sulaco re his C280's hesitation to go to 4K RPM. I checked my voltages and they are good, 13.92VDC max even revved up.

Any ideas gentlemen? The sole MB dealer here is not really that competent in diagnosing issues like this and I dont want to bring the car there until I have an idea of what to look for.

[hvmercy]

How about the quality of gas you're using? Perhaps it's time
to have your fuel system checked out. (filter etc)

[jnenad16]

sound like you have a plugged intake or exhaust.

nenad

[BongC36]

Thanks for the replies. Just had a tune-up, new fuel filter too.

Plugged exhaust? How can I determine that? Funny but the Service Advisor of the dealership mentioned that also, he suspects a plugged CAT but his solution is to buy a new Cat without checking if the old one is bad

[BongC36]

Some "Italian tuning" seems to have helped the car some. Now the hesitation of 'flat spot' is only at around 3400~3600 RPM where there is a perceptible pause in the acceleration. Once it passes that point then its business as usual, rapid climb to redline then full-throttle shift to the next gear.

This only happens at WOT. If I drive with part throtlle the 3400 RPM barrier is passed uneventfully.

I did nothing yet but to check for any vacuum leaks and measure alternator output voltage range.

My gas is 96 octane (RON) because there arent any superplus (98 RON) available here in my country.

[jnenad16]

Originally posted by BongC36
Thanks for the replies. Just had a tune-up, new fuel filter too.

Plugged exhaust? How can I determine that? Funny but the Service Advisor of the dealership mentioned that also, he suspects a plugged CAT but his solution is to buy a new Cat without checking if the old one is bad
most shops used to perform backpressure test, but I rarely see it these days. we dont do it either. we usually test drive the car and run a few performance-related tests. as for the cat, there are some treatments that claim to clear the clogged cats, but I haven't tried any of them yet.

nenad

[ship]

if it's only in that 200 rpm range I would take some pin out readings on your tps sensor...

the only plugged cat i've seen caused the whole car to bog down after it built a few rpm...

I'm thinkin TPS???

[jnenad16]

Originally posted by ship
if it's only in that 200 rpm range I would take some pin out readings on your tps sensor...

the only plugged cat i've seen caused the whole car to bog down after it built a few rpm...

I'm thinkin TPS???
that was my initial thought, but it would set off CEL, sometimes.

nenad

[BongC36]

TPS=Throttle position sensor? The Check Engine Light is not lit but the SRS is.

[ship]

I am not too familiar with the C36 but did one on a domestic recently and it didn't throw a code.
OBD 1 cars are really strange, streaming data is the only way I have been able to work on them..

and mbbraingears is down :bored: