Thoughts on lack of power.

[dewme5]

I just picked up an 89 325i Auto. It's my first E30 though.

The car was a impound sale, so I know nothing of the prior history. The engine is tight, sounds good, and passed the smoke test with no problems. Everything I've done so far, has little by little improved it's condition, but I feel like I'm way down on power. The only thing I have for comparison, is a modified E60 535i pushing 18psi, so my butt dyno is probably a little off.

Looking at stock performance numbers, 0-60 should be in the 7.7sec area, and I'm pretty sure this E30 can't do better then 10sec right now.

When purchased, it was a little rough running, but reliable.

AFM looks brand new, and the resistance strips are perfect.

In the last week, prior to attempting to smog.
New coolant temp sensor
New intake bellows
New walbro 255 fuel pump
New 3bar bosch fpr
New fuel filter
17/lb injectors, and chip from mpowerful
run for about 50 miles with fresh gas.
adjusted valve lash
20/50w GTX oil change

Smog was a fail for Hydrocarbons. Test guy said coil wires were erratic while trying to get a signal.

So, this week
New bremi wires
New bosch coil.
New sparkplugs arrive tomorrow.

I get a free retest on the smog, and I need to do that tomorrow.

So, suggestions?

I'm guessing the cam might be one tooth off, but I do not have the time to check it right now.

Am I expecting to much? it can't even do a one wheeled burnout.

[Andy.B]

Imagine starting out in a manual transmission in second gear with a slipping clutch.

That is essentially what you're dealing with.

I swapped my gf's auto to manual and it was a night and day difference.

[LJ851]

Cam timing is a good place to start. An auto car is as fast as a manual car at full throttle, it's the part throttle that is so slow.

[dewme5]

I'm contemplating the manual swap. Downside, is that I have no garage, or tools. I'm working in Cali as a contractor right now. My garage and tools are in Florida.

Instead of going crazy, I wanted to keep it simple. Decent interior. Engine that will pass smog. fully rebuild the suspension and bushings. Rims tires. About that time, my job should be finishing up here, and I'll sell this car. If I don't become hopelessly attached to it. I have a 85 635csi project back home that will go a little nuts. But then my oldest kid could probably make good use of an E30 for his 17th Bday... hmmmmm

Full throttle feels decent. Anything below 3k is useless. Just trying to make sure it's a "problem", and not just my expectations being off.

[LJ851]

I'm contemplating the manual swap. Downside, is that I have no garage, or tools. I'm working in Cali as a contractor right now. My garage and tools are in Florida.

Instead of going crazy, I wanted to keep it simple. Decent interior. Engine that will pass smog. fully rebuild the suspension and bushings. Rims tires. About that time, my job should be finishing up here, and I'll sell this car. If I don't become hopelessly attached to it. I have a 85 635csi project back home that will go a little nuts. But then my oldest kid could probably make good use of an E30 for his 17th Bday... hmmmmm

Full throttle feels decent. Anything below 3k is useless. Just trying to make sure it's a "problem", and not just my expectations being off.

Sounds normal. M20B25 does not make power til about 4k which is why the auto cars feel so sluggish. If you don't have the gas pedal matted the trans will shift around 3k or less and you basically drive around in a very low power zone all the time.

If you shift it manually with the gear lever you can control when it upshifts and it will feel much faster/better. Keep it above 4k and it is peppy.

[dewme5]

"Peppy" is probably the best word for what I'm feeling.

[Liquidity]

If you don't have the gas pedal matted the trans will shift around 3k or less and you basically drive around in a very low power zone all the time.

If you shift it manually with the gear lever you can control when it upshifts and it will feel much faster/better. Keep it above 4k and it is peppy.

All you have to do is adjust the detent cable and it will shift later. I adjusted mine as far as the cable would go and still allow full throttle. Very rarely do I have to manually intervene with the shifter to keep the car in the gear I need.

[LJ851]

All you have to do is adjust the detent cable and it will shift later. I adjusted mine as far as the cable would go and still allow full throttle. Very rarely do I have to manually intervene with the shifter to keep the car in the gear I need.

Mine was set at bmw specs, i solved the problem with a manual transmission years ago.

[mpowerful]

Could be running a tooth retarded on cam timing. Other things to check. Fuel pressure. Sometimes the return line in the tank gets clogged. Also cat converter if its coming apart can cause poor performance and failed hc test. There was something else i thought of and forgot haha. Morning time. Need more coffee. Are you gonna bring this car back to panama city anytime? New orleans isnt all that far.

[mpowerful]

Oh and of course vacuum leaks. Tps too. If tps doesnt turn off the iacv itll cause it to essentially vacuum leak with throttle open allowing richening of mixture.

[dewme5]

0 vacuum leaks. I've done a pretty full job of testing those. Smoke test, spray test, visual insp, and pressure test.

I'll test the TPS when I go back out this morning.

The shifting is fine. I don't mind manual operation when I want more RPM out of it. Smooth cruising is a nice.

I'll just have to check if the cam is 1 out, after my trip.

Thanks for the help, I was just trying to make sure there is not something simple I had missed. This is my 5th BMW, but the first 3 were not considered projects, so I didn't work on them much. I had a 318ti with more power then this 325i, which makes me think something is wrong. Once I get back and check the cam timing, I'll dig this thread back up, and update it.

[Liquidity]

Oh and of course vacuum leaks. Tps too. If tps doesnt turn off the iacv itll cause it to essentially vacuum leak with throttle open allowing richening of mixture.

That's false. The ICV does not take its air from before the AFM. All air the ICV feeds into the engine is metered. The ICV being stuck wide open cannot do anything but cause the engine to idle high.

[mpowerful]

It is metered air true. I stand corrected there. Although a stuck open IACV would cause other headaches for sure. Anyway, if sensor isnt taking the car off idle it is still telling the DME to consider idle fuel etc.

With that being said I thought of something else. The coolant temp sensor for the DME. When they start to fail it can certainly cause a rich condition. They are very cheap to replace if it hasnt been done.

[dewme5]

Coolant temp sensor was the first thing I replaced (updated the OP). I rank that #1 on the best bang for the buck change you can do to a car, simply from the negative effects a bad one can cause!

IAC works smooth, responds well, and ohms out.

[dewme5]

I keep plugging away at things, trying to make progress. I had set valve lash at .010" just a few days ago, but there was still more valve train noise then I think there should be. I decided to take that down to .008", and that mixed with running some Seafoam aerosol through the intake seems to have made a favorable difference. Nothing super, but noticeable power gains. Running the android "aDyno" app, there was a full 1 second difference, but still way down from what it should be.

Ran aDyno to time a run, and used a HP calculator from the internet, and came up with these numbers.

Your HP computed from your vehicle ET is 99.57 rear wheel HP and 110.64 flywheel HP.
Your HP computed from your vehicle MPH is 153.98 rear wheel HP and 171.08 flywheel HP.

Guess this is a little more promising then I was thinking, when it comes to the engine working correctly.