Low power at higher speeds

[kingston]

Guys,

I've just finished (mostly) a 24V swap into my `88 325. I used an M50TU from a `94 325is (manual transmission). ErikT on R3V made the wiring adapter.

I picked the car up from the exhaust shop today. I'm running OBD-2 headers modded to wok on OBD-1. The O2 sensor is in the rear bank of the headers, with a bung plug in the front bank of headers and in the bung plug on the single tube farther back.

I am running a Getrag 260 with a 3.73 LSD diff.

So the car sounds great, and pulls strong at lower speeds. At higher speeds (highway speeds), I don't seem to have much power. At 60, going up a mild hill, the car doesn't want to accelerate in 5th, and even dropping it down to 4th doesn't seem to make much difference.

Car idles fine, there's no CEL. Used the brown temp sender from my M20 on the head.

It just kind of feels like the car is being strangled at higher speeds. Again, at low speeds, the car seems to rev cleanly all the way to the redline.

Any suggestions??

Thanks in advance!!

[e30rapidic]

speed sensor hooked up?
how big is your exhaust? all new stuff?

[blackhawkimpact]

Could be the speed sensor. Is your tach working?

[MattM]

your o2 sensor is doing you no good where it is. Its only monitoring the back 3 cylinders. Id move it to a point where all cylinders are firing through(X pipe or Y pipe are the best spots)

[328ijunkie]

Vss

[phreshkid]

Did your engine come out of a smashed car? Sometimes upon impact, the force can be large enough to retard cam timing a few degrees left or right. I'm not exactly sure how it works but if you have a means to do so, inspect your cam timing make sure everything is within spec.

Also exhaust has a lot to do with overall flow of the motor. Good, free flowing exhaust does wonders for these already restricted motors.

[kingston]

Guys,

Thanks for the responses. I was out of town Friday and part o Saturday, then headed straight to a Euro meet.

A couple of thoughts on your responses:

speed sensor hooked up?
how big is your exhaust? all new stuff?

Speed sensor is hooked up. The exhaust headers are OBD-II modded to wok on OBD-I. The rest of the system is stock E30 325is (and sounds AWESOME!).

Could be the speed sensor. Is your tach working?

Tach works fine.

your o2 sensor is doing you no good where it is. Its only monitoring the back 3 cylinders. Id move it to a point where all cylinders are firing through(X pipe or Y pipe are the best spots)

Levent and Joel at Guten Parts said basically the same thing. I will be making that change in abot 2 weeks (next payday), and I'm hoping for an improvement!

Vss

I'm sorry, I don't understand this response. :(

Did your engine come out of a smashed car? Sometimes upon impact, the force can be large enough to retard cam timing a few degrees left or right. I'm not exactly sure how it works but if you have a means to do so, inspect your cam timing make sure everything is within spec.

Also exhaust has a lot to do with overall flow of the motor. Good, free flowing exhaust does wonders for these already restricted motors.

Cam timing was reset when I changed the head gasket (which was just maintenance; figured with the engine on a stand I should just do it). I might explore other exhaust options down the line.

A few other observations. My Aux fan is not coming on. Pushing the 'snowflake' button doesn't make it come on. The car is, thus, running warmer than I want it to. I've bled it a couple of times now, and it seems slightly better, but not where I want it. When I've driven the car on the highway, the engine has gotten pretty warm, and I think that is part of the issue (intake air being hot).

Also, my left front caliper is (I think) sticking occasionally. This may be giving the impression that I've lost engine performance, when in fact my car is trying to brake slightly by itself. At higher speeds, the friction increases, which in turn increases the drag. I'm not 100% sure that is what is happening, but I will be rebuilding my calipers next weekend!

Thank you guys VERY much for your responses. Please keep `em coming, and I'll post updates here as well.

Cheers!!