mytrplseven

Will this ever finally get right? Now that I've replaced so many things I can count, I thought I finally had it fixed after replacing the TPS with a new Bosch unit. The car goes to redline with ease. But under normal acceleration I still have hesitation issues.

Tomorrow I'm going to repressurize the intake and see if there's a possitility of a vacuum leak that I either missed or caused with all the fiddeling I've been doing. Also going to go through the AFM one more time to verify there's no issues there.

So far: new TPS, new NGK plugs properly gapped to .028 and indexed (the bosch plugs I pulled looked perfect), rebuilt injectors w/new connectors, new O2 sensor, fuel system pressure tested in total, new coil, wires, cap and rotor, new intake manifold gaskets, new belts, rollers, wp, all front and rear rubber seals (including the leakiy ones in the TB), clutch assy, short shifter and new tires and Cayman wheels. Also inspected the ECU to see if there was any indications of bad solder joints and cleaned all the connectors I could get my hands on. You'd think by now I'd have gotten a break and the car would at least accelerate smoothly out of consideration

This thing has plagued me since I bought the car 3 years ago. It's just plain irritating. I can't keep driving it around in WOT just to keep a smile on my face.

william_b_noble

check the air flow sensor for a worn part on the carbon track, move the position of the wiper to track on a new area if there is wear through

Reimu

You also might want to crack open the DME and look around. This was the cause of my hesitation and eventual no start.

87944turbo

which wires? I put on Magnacors and found they were causing a stumble/miss around the middle of the rev range. Went back to the old stock wires.

mytrplseven

I had already re-worked the AFM and relocated the wiper last year. The cover on the AFM had been removed by the PO and wasn't really resealed when I got the car. I took the DME apart and checked for bad joints and cleaned all the connectors. I don't remember which ignition wire mfr I put on the car. It was over 3 years ago and I wasn't sure there was an issue with one over the other. I guess it's possible. There's such a long list of possibilities for this problem, I've just been walking through them one at a time. Car runs great outside this problem.

william_b_noble

the 944 is very sensitive to vacuum leaks and surprisingly sensitive to plugs and ignition issues - stumbling could be either - my first quick thing would be to clean the inside of the distributor cap. I always use OEM wires (Beru) because of some less than excellent experience with others -

mytrplseven

Today I replaced the AFM with a known good one and rechecked the vacuum for any possible leaks. Nothing worked it's way loose since I took care of that the last time. After buttoning up everything and driving until up to normal temps, the hesitation on acceleration (except WOT) is still there. I guess the next thing is the wires, although I would have expected the WOT to stumble if there were any ignition issues. My neighbor who has raced cars for years said the same thing. At this rate I'll have a new engine from buying all the new parts. The car idles smooth and accelerates like a scalded cat under WOT, except under normal acceleration. Annoying.

mytrplseven

Update: bought a new reference sensor because the connector on the bottom one was all broken and crumbling. Also bought a female connector to totally rebuild the defective connection. Don't know how both parts got broken but after disassembling the femal connector and crimping and soldering new pins and snapping them into the female connector, I installed the new ref sensor and the car still hesitates slightly on partial throttle. WOT is really WOT. It goes to redline without hesitation. I'm thinking that next will be Beru ignition wires while I chase this little gremlin.

william_b_noble

the car is very sensitive to ignition wires and also to the distributor cap and rotor - given all that you have changed, I would consider getting a complete set of OEM cap/rotor/wires - I've had excellent luck with both Mahle and Beru - take your pick

mytrplseven

Yeah, I'm looking around for a set of Beru wires. Funny how each thing I've done has made the car a little bit better. Feels like a "real" Porsche.

mytrplseven

Well, I got a set of Bosch wires with Beru connectors from a member. They checked out evenly with an ohm meter and were in excellent shape. When I pulled the wire (with great difficulty) from the coil pin on the existing cap it looked very corroded and there was what I would describe as arc welding slag all around the pin. This cap is new and without removing the wires I would never have considered there would be an issue underneath the rubber. Now: new Bosch cap, NGK plugs, wires that are WELL connected and initially, I still have the hesitation under "soft" acceleration. Idle and and WOT are normal. I'm going to pull the DME and see if the IRQ has been messed with by the PO and possibly look at going to position 2 to see if that changes. My thinking is that I'm running a bit lean under these conditions. I also have a shop near Pompano Beach that will take a ECU off the shelf to swap out to see if the problem is there.

NM'87 951

Will be using this thread to hunt down the solution to my throttle hesitation, if it is still there when I get the vacuum kit installed, and clean my grounds.

Thanks for the continued info.

mytrplseven

You in Lordsburg, Deming, Las Cruses? I love NM. I bought my '87 na from a Dr. in Santa Fe and drove it fearlessly to Floridal