Original 93 with throttle stutter
 

I've got an orignal 93 Gen 3 with a serious throttle hammer problem at part throttle around 2500 to 3000 rpm. Its usually livable but I just replaced plugs and wires and problem is much more acute. A Mazda tech told me it was pinched hose of some sort but I never found one. It was there to some degree when I bought it new with 1 mile on it so it's not a wearing part. Shouldn't be rubber deterioration since it's from that age.

First, does everyone have this problem? I've never worked on this car so I'm not sure how the electrics work as far as VSS, TPS, MAF etc.

All help appreciated!

Joe STill:confused:

Welcome Joe! First thing order up a boost guage and mounting pod, then we might be able to help better. Until then it's just guesswork and trial and error, which will only frustrate you. Be sure and post your mods if any. As original owner, how many miles do you have on it? Heat rots and actually "petrifies" the 72(!) vacuum hoses. The FD has no MAF or VSS, and you could have a double-throttle control problem, which should disconnect after warm up.

Thanx Toadman. I have been needing RX7 people to "talk" to for years!

Black 93 touring just over 40k. A truly pretty piece of auto art. And what a rush! Speaking of which, do most of you find these stock cars hard to drive smoothly? I have to use a lot of clutch (compared to my old Corvette) to compensate for fluctuations in the throttle (with no pedal change mind you) and of courst to compensate for lack of torque at lower rpm.

My dealer sold the franchise to the Mitsu guy and you can guess just how interested they are in "learning how to work on my car. I let em do plugs and wires and they left me an elbow crease in the top of the fender ("Well were sure that was there when you brought it in")

Suggestion on boost gage? I wouldn't mind some perfromance upgrades but I'm strictly autocross- not dragstrip. Suggestions?

Joe

Joe,

You should download the shop manual PDFs from one of the tech sites. Section F is all about the fuel and emissions system, and has some really interesting information about what happens when the engine is in different states (hot/cold, different RPMs, different electrical loads, etc.) I'm sure you'll also get a lot of good information from some of the technical guys here on the forum, too. Reading the manual is enlightening, though.

--
pedalpusher

I have the boost gauge Peter Farrell distributes. I also have a cheapo gauge from Pep Boys for troubleshooting. When t-ed into the same place, I see absolutely no difference in readings.

I'd have 2 Pep Boys gauges if I could turn back time.

Is the car's tractibility really that closely related to turbo performance? I guess since I specified 2500 to 3000 as the "dead spot" and if I understand that's where turbo 1 picks up maybe it is turbo trouble.

As I went to lunch today I took off from a light and the thing just about died like a fuel shut off bu picked up 1 second later. This cas also hammers back thru the drivetrain off throttle when coasting cold(like down a hill). I have to clutch it to stop the shudder in the drive line.

Maybe it's haunted but the fact I've lived with it 9 years tells you what I think of it. BTW, at full tilt it never skips, misses, pulses, etc. Only in town non-ticketable driving brings out the demons (and of course before fully warmed up).

Anybody current subscriber to Alldata so we can check Service Bulletins?

Joe

Here's some good reading for you. Good luck.

http://www.scuderiaciriani.com/rx7/3k_hesitation.html

I'm having the same problem and will start troubleshooting this week-end.

Silent Strider, how in the world did you find a site on exactly the problem I described? I'm new to this website but, damn!!! Really appreciate that.

I'm printing now for later review but I will not forget to give you updates in case you are helped in return.

Mine pause was truly there at 1 mile as I expressed concern to the salesman who prceeded to run the s__t out of the car which does not expose this problem. It is worse now with new plugs. Mazda replaced the computer on my first trip under warranty claiming that was the trouble. Here again its worse some days rather than others so as the plugs got older and performance degraded slightly it dropped off my radar.

Thanks again!

This wasn't entirely fair. The PFS gauge appears well made. To me it's not worth the extra money for a nice looking gauge when the cheapo works just as well.

Stryder, I've read the reports and intend to do battle with grounding this weekend if possible. I think I'll do the temp wire to try and isolate.

Joe,

If you have the infamous 3000 RPM stutter, and are amenable to modifying your car, you might consider an aftermarket ECU. I bought my FD new, also, and it had the same stutter for years. The dealer tried a ton of voodoo, but never eliminated it. Then I bought an A'PEXi Power FC, and the problem vanished. I know this has been the experience of at least a few people here on the forum. I guess aftermarket voodoo works better than dealer voodoo.

--
pedalpusher

How long have you had that aftermarket ECU? I've read that you case "mask" the problem by enriching the fuel but this is by far from an actual fix. I've also heard of people installing an aftermarket ECU and the problem comes back after a couple months. I don't have the $900 to throw on an ECU and would like to get as much info on it as I can. I don't plan on heavily modding my car as it performs to my expectations. I may do some preventive modding to improve reliability and maybe even a little horsepower.

The only two problems I have with my car is the hesitation which is erratic and unpredictable and a small ticking noise from under the hood.

If it's just a little hesitation, just get a grounding kit. Pull all your current grounding points, make sure they are making good contact. Clean off any gunk, and then run some extra grounds.

Some people have solved or muted their hesitation with an aftermarket ECU, however, it may just bandaid the problem, not really fix it.