My motor runs good from Idle to ~3500-3600 RPms then it hesitates (loss of power) like the fuel or fire is disrupted unless I pump the peddle. This lasts untill ~3900-4000 RPMs where it continues to accelerate. This happens in all gears accept 1st (guessing there is not enough back preasure in 1st). It doesn't just happens at full throttle it also happens if I try to cruse at that RPM range.

I have replaced and adjusted the TPS and the symptom has not changed.

What is the ECU doing at this RPM range that could cause this. I think the ECU doesn't like some input it is getting at that time or could it be the distributor?

Looking for suggestions.

Most of the emissions stuff is removed.


UPDATE:

Issue fixed after many months of analysis.
Problem was car was running too lean A/F would spike around 3700 RPMs to 17:1 (bad). A\F was below 13.5 :1 above and below that RPM range.

What I went through. 1st I checked everything anyone suggested. Then I built a complete 2nd distributor from parts (no change to problem), Diffrent TPS (no change to problem), diffrent ECU (no change to problem), New plug wires, plugs, coil, had injectors cleaned and flow tested (no change to problem), addded wideband A/F meter and noticed that the A/F mixture was too lean. bought a calibrated MPS (no change to problem). Purchased an LCR meter and went to work adjusting my origional MPS. Started with numbers from MPS writeup but was still to lean with hesitation. Made some adjustments based on what I was seeing on the A/F meter and Vacuum gage and now it runs great. I'm running as high as 13:1 but spend most of the time between 12.2:1 and 12.8:1 except during WOT when it drops to about 11:1. The car runs better than it ever has during the 1 year I've owned it.

I think that if you have a 75-76 car which was designed with all of the emisions crap on it and you have taken all of it off like I do you are most likely running lean. The motor now needs more fuel. Just getting an MPS that is calibrated to the factory numbers didn't fix my problem.

The bad news is that it took me almost a year to fix it and I purchased a lot of parts that I didn't need.

The good news is that I have a great running car and a set of good spare parts (ECU, MPS, Distributor, TPS)

I went thru about this time last year . If you do a search on my id you will find that thread, at the end, it was the advance on the distributor that was stuck. Remove the distributor and suck in and out the two vacuum lines, watch for movement on the arms.

That is where I would start .

That's the place to start as gummy 40 yr old grease in the adv weights can cause this. Advance should be all in by 3500 rpms so if its stuck it causes this.

I have a hand vac and will test out the advance and retard to see if the plate sticks. Can I remove the plate to clean it without removing the whole distributor?

While you have the hand vac out check to see if the MPS is holding vacuum...

I'm ahead of you on that one, The MPS hold a vacuum and ohms out good also.

Thanks for the suggestion.

disconnect the TPS and run the car to that RPM range. Hold the throttle at one set range like 2800RPM. If the hesitation goes away, you have a bad TPS switch (as in worn out).
Phatnine11

The distributor removal is actually easy. There is a dog drive, so you don't need to worry about realignment when you put it back in. If you look down the hole after pulling it only goes one way. You only need a 10 mm wrench - I like a gear wrench for this.

Have you lubed the vacuum advance lever and center-shaft felt lately? The felt should be lubed once a year to lube the advance weights below it. Use a drop or two of 30 wt or 3-in-1 oil.

Thanks I will do that tonight, where on the shaft do I lube, at the point where it meets the plate? After I lube it I will us my vacuum to advance the distributor. When I release the vacuum it should freely return to no advance.

I am still working out all of the neglect from this car which I bought 2 months ago. This is my 1st Porsche 914 but I do have experiance with VWs.

Is the removial the same nut that I loosen to adjust the timing?

My '75 did the same thing. I can't explain why it worked, but replacing the relay board solved the issue.

No, you do need to loosen it enought so that you can rotate the dizzy to expose the clamp which is held by a 13mm bolt. This one must be removed. The dizzy is a piece of cake to remove and re=install.

I took out the dizzy to clean it (it was easy). I'll post some pictures when I get to my computer, on the iPad now.

It wasnt to bad but I did clean it completely inside and out. I did find that the ground strap on the points plate to the case plate had been cut off. Could this contribute to my problem? I went to radio shack but they didn't have any braided wire. Any suggestions as to where I can get some?

Bump