TeamSwift

Posting more for documentation, but if this reminds you of something your car did and you fixed it, I'd love to hear the story...

My 94' GT has a problem between 2k and 3k rpm at low loads. There is a slight surge and hesitation at a regular frequency that can sometimes also be felt in the steering wheel, can also be heard in the exhaust note. It's worse when it's cold.

My guess is that something is not as square as it should be somewhere in the drivetrain. I have one of Balli's LSD's, and recently installed a new clutch and machined, lightened flywheel--survey says any issue is likely to be related to what you just did to it ...But I did that work a bit back and didn't notice an issue right away for sure.

Is anyone familiar with failure modes for torsen diffs? Seems to be grabbing well, but unevenly when it hooks up--pinion gear not installed square?

Oddly, it is impossible to notice anything wrong when running the car hard except for the stutter in the front wheels as the diff hooks, if it is indeed related to the other problem--seems like it's done that for a very long time now. Also oddly, it seems to improve slowly as the car is driven beyond initial warm up and for significant distances.

I changed trans fluid for the first time since I put new bearings in it and the fluid did not look great either, lots of metal on the magnets

Just to make it unclear how many small issues I am chasing, it's hard to start when cold too. Somebody tell me it's all just an ignition issue so I don't have to drop my trans again! Do I remember seeing a post somewhere mentioning that a car with a failing MAF needs the pedal pumped to start quickly? Because that's whats going on with my car.

If it's colder than 50, car will start but it takes a worrisome amount of cranking, unless the pedal is mashed quickly and repeatedly a few times. Then if fires up instantly...

I checked the air gap at the distributor, replaced the coil for the hell of it, checked all wires and installed new plugs.

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I have never seen a MAF go bad slowly, they either work right or they don't.

A couple of things I would check though:

1. The wiring at the MAF connector. I have seen those break off TWICE on my car and never through a check engine light.
2. Check all the rubber hoses, intake tube and vacuum lines. Any leaks in those can cause some weird issues.
3. When was your last fuel injector service? The factory injectors are terrible and I have gone through more then a few sets of them. I am currently looking for a non OEM replacement.

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"Don't argue with stupid people. They just bring you down to their level and then beat you with experience."

Thanks for the interest and leads:

1. my MAF connector is intact but I see the potential for stress on the connection. How did you catch it when you had problems, and what did you do to fix it, i.e. did you pull a random, similar connector from a junked car and splice it in or what?

2. Well yes, sigh. Of course, like I'm pretty sure 95% of Swift owners, I threw out the stock stuff and fabbed up my own setup. I'm pretty sure it doesn't leak...much? I did just have it off, improved some things, put it all back on and tightened it up good with no change. I don't think that's it, but I'll do a smoke test at some point again and see if I catch anything.

3. I had the injectors cleaned (but not flow benched) maybe 30k miles ago with an ultrasonic cleaner at a local shop--not a dedicated setup for injectors. I had problems with either #2 or #3 that couldn't be solved by cleaning so I replaced those two with the "green bottom" injectors, which I had cleaned at the same shop. Mine are therefore mismatched (#1 and #4 are Mk3 injectors, #2 and #3 are Mk2) and have not been flow benched. It's run smooth as butter like this for years (until this new issue), but I'm with you on there likely being better solutions out there. I know you've followed my ECU tuning discoveries, so I can easily adjust my tune to deal with a swap that does not flow exactly the same.

If you or anyone that reads this is aware of a good drop-in swap (shape, o-ring size and connector, not necessarily cc's) from a car modern enough to have improved injectors, but old enough that they can be found somewhere for not too much $$, let us know FWIW there's a good u-pull yard here and I can probably pick up a set for almost nothing. I'll bring one of mine to measure up and see what I can find...

_________________

Spanish Inquisition Racing chip burning service--build yourself a custom chip!
http://www.teamswift.net/viewtopic.php?f=17&t=57216

The first time I had to fix it, I was doing some work on the car and when I was done I went to start it and it wouldn't start. After some digging I found a wire broken off the sensor. The second time, I was trying to get the car through an emissions test. It was just barely failing the test. I had the engine running to check for codes while I was doing some other checks when I noticed the CEL was flashing a code other than 12. Both for the MAF sensor, one voltage too high and one for voltage too low. Anyway I opened up the plug again and sure enough a different wire had broken off. I didn't have a spare connector so both times I used a small straight screw driver and forced the existing terminal back out through the connector and then soldered the wire back to it. The fitment is tight enough that once I cleaned up the terminal it stays really good in the connector. Haven't had an issue since.



Yeah having the mis-matched isn't great but you do what you have to. In my case I had a set of MK3 injectors that were leaking making the car hard to start and I had to use an old set of MK2 injectors. But I am on the look out for any kind of replacements. You are fortunate in that you have the ability to adjust the tune to dial back the flow if you were to buy something larger. I do know our injectors are only 2ohm units so there is no harm in finding ones that are of a higher impedance.

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"Don't argue with stupid people. They just bring you down to their level and then beat you with experience."

Well the car still starts hard unless I pump the gas (very hard, after a few quick stabs of the gas it fires instantly though, so whatever it's hard to be motivated to troubleshoot given there are no other issues).

The rest of the problem turned out to be tires.

Just tires.

I can't believe that vibrations from slightly out of balance tires (barely noticeable at highway speed) could actually be heard in the exhaust note, but the clue is that the vibration could be felt in the steering, even if it wasn't all the time or very strong.

I just put on new 185/60 r13 "daily driver" tires so I had an opportunity to double check. The nature of the problem changed (less in the exhaust note more in the steering), but it was still there, so that was a clue. Rebalanced, made it worse. Did some research, realized I could/should properly match mount the tires by lining up the yellow dot with the valve stem when mounting. Did that, rebalanced again.

Problem solved

I believe the fact that my 15" tires have some minor flat spotting from competition + they are very sticky and don't like the cold + the wheels are actually quite heavy and maybe have some runout + I have a lightened flywheel + I have stiff poly engine mounts, all contributed to a minor tire balance issue that really, honestly, felt like it could be some sort of ignition or other engine-related driveability issue.

Crazy.

With the new 13's properly match mounted and balanced, the car is as smooth as butter again

_________________

Spanish Inquisition Racing chip burning service--build yourself a custom chip!
http://www.teamswift.net/viewtopic.php?f=17&t=57216