Within the last 3 weeks, my stock 93 has started bucking when i'm at cruising throttle. it's as if i'm tapping the gas pedal - power, no power, power. if i give it more gas, it goes away. idle is fine, and the car is as fast as ever under medium to full throttle. it also stalled twice yesterday when i had the AC on and came to a stop, which was what my 2nd gen always did when the TPS was out of adjustment.

i'm pretty sure it's the TPS. Anyone have any tips on adjusting it? I've done it on a 2nd gen before - is it similar?

Also, how much slack should be in the throttle cable? When i was fooling with it, i noticed there seems to be quite a bit of play before the throttle is actually opened. shouldn't the cable be fairly tight?

thanks in advance for the help!

 

I have the same problem. I have been thinking about it and it happens only when its below 3k rpm. Thats either because its just part throttle or its the primary injectors are bad/dirty. Also I have all the records for this car since new and its never had a fuel filter changed from what I can tell. Thats my other guess. if you find out what it is PM me with the answer. I will add it to my laundry list. Thanks

 

I just had the fuel filter changed - it started doing it two days after that.

It could be a bad injector, but I also noticed tonight that it looks like the dealer (yeah, i know) spilled some oil around the spark plugs, so that could be part of the problem, too, i suppose. Although it would seem then it would do it at idle, too.

 

ok, i'm wrong. it started bucking BEFORE i had the fuel filter and spark plugs changed - that's why i did the fuel filter in the first place.

so now we're down to TPS, bad injector, and about 500 other possibilities.

 

I would guess it's the TPS or a vac leak such as a leaking lower intake manifold gasket. There is some how-to on the TPS adjustment. Look at the link section on this site for Scandarini's (sp?) site. He's got some good instructions.

 

I woudl test the TPS before I adjusted it, a complete procedure with proper operating ranges, etc are in the shop manual, I suspected mine too, luckily I have a PFC, so I just have to look at a screen to know it is working properly. I rememebr the wide band reading shoudl be below 1 at idle, and about 5 and full throttle if that helps at all.

 

thanks for the input on the tps. i planned on testing it - that's why i'm not getting around to it very quickly since i haven't had time to get the parts to build my own tester. i downloaded the shop manual last night so i have all the official instructions, as well as scuderia's instructions.

 

My 93 used to do the same thing when using the cruise or under light throttle and worse when the headlights were on I always thought it was typical 7 hesitation problems. If I had kept that 7 I would of put pfc or some ecu upgrade and hope that would of fixed it. Sorry I have no helpful advice but were did you download the manual?

 

1 BAD 7,
Check the upper clutch pedal switch (NOT the starter interlock switch). It is supposed to send a ground to the ECU when the pedal is in. Why do I suggest this? Because you stated that it stalled when coming to a stop with the AC on. My car had a bunch of idle wierdness / bucking and etc. and this is where I traced it to. It's a cheap part ($14) but can be repaired, it is probably a broken spring inside the housing.
Cliff

 

hmmmm....that's a new one. i'll add that the list of things for ryan and i to check when we tear into it monday thanks!

 

ive also got the same problem

 

come to think of it, sounds like o2 sensor, it would make sense that it disappears on throttle because the O2 at that point goes on open loop, and is not used.

if you have over 60k miles, and hasn't been changed, get the Napa ford escort 3 wire part # os204 1986 ford escort, 39$ what the hell it is worth a try.

 

Any of you ever try Techron fuel treatment? I just added a quart about a week ago... and it seems to help smooth out the bucking significantly. My FD would buck pretty intensly, almost making it a chore to drive smoothly (especially very light throttle/cruise). I would have to say that the bucking is almost gone, with just a mild hiccup here and there... but definitely worth a try for just $5 a bottle. Just my $.02

 

(sigh). I took it to Ryan's house last Monday to test the TPS. We were getting some really off-the-wall numbers, waaaay over what spec is. Were we doing something wrong, or is it possible for the tps to be that out of whack and the car still run? i've also read that the ecu compensates for anywhere from a 5-15% variation in the tps - is it possible that's why it only does it some of the time?

i can go for a day or two and not have a problem, but then i have times like tonight where i'm not even sure i'm going to make it away from a stop (or home!) it's bucking so hard. my rpms go up and down with the bucking - it's like i'm engaging the clutch and popping it out while i'm driving. other times, it's just a mild surging feeling.

it seemed to be getting better, but tonight was the worst it's ever been. it was so bad my radar detector fell of the windshield!!!

i also think it may be running rich. i don't smell anything, really, but if i'm parking or when i shut if off it's been popping alot. sometimes i get a rotten egg smell if i'm idling and the wind is blowing right, but it's always kind of smelled that way (and no, it's not me).

so, when's the rx8 coming out....?

 

I'm chasing the same (or similar) problem on my 2nd gen TII - Do a search on "Violent Hesitation" to see what I've done so far. My post is in the 2nd gen tech support group. I'm still waiting some feedback. You may want to follow it, and hopefully between the two of us (and all the help out there) we can lick this damn thing!

 

KHONEY - I read those posts (thanks), and noticed the O2 sensor and intake manifold leaks are listed as possible culprits by a couple people. i'll hopefully be replacing the o2 sensor today.

could a leak in the manifold be the reason i'm getting that rotten egg smell? i really can't believe this is the problem, because i just spent a little over a grand having a bunch of work done a year ago, and the manifold gasket was part of that work. kirk did the work, before he packed up for OK, so i doubt it was a shoddy job. could this also be causing it to run rich, therefore making those popping sounds from the exhaust (i only get it if i'm on and off the throttle, such as when parking, or when the revs return to idle).

 

paully d at aim doesn't think it's the tps - he's never seen a 3rd gen tps get out of adjustment....

 

there's a new turbo shop opening up this coming week in Fenton, MO. went to talk to the guy today, turns out he's pretty knowledgable about 7's. tomorrow i'm taking it up to autozone to get the battery and alternator checked, and within two weeks i'll be putting in a new o2 sensor and getting the injectors checked/cleaned.

i'll keep you posted on what i find....wish me luck!!

 

Got the alternator and battery tested...Alternator is ok, but the battery is bad. getting closer to the solution...i hope!

 

I don't know if these are causing your hesitation but the rotten egg smell is caused by one of two things, a clogged fuel filter, or a clogged cat, and I would think either one could cause hesitation or bucking. But I could be wrong?

 

Fuel filter is about a month old, so it's not that. I think there's a chance at least one of my cats is going.

I put in a new Optima dry cell battery last night - absolutely no problems since. I even drove last night with headlights, foglights, AND air condition, and no bucking!! I'll give it a few more days before I declare success, but so far so good

 

My bucking problem goes away with cooler weather. What's your weather been like lately?

 

Every once in a while I will get the same bucking symptoms.

It came between 2200 and 3000 RPM with it disappearing after 3000 RPM.

I was running lights, AC and Fan mod all at the same time. Immediately when the bucking started I turned off the fan mod (bucking still there) turned off the AC (bucking gone) turned the fan mod back on (bucking returns)

I ran the car back home (10 min in the rain with temps outside around 80)

Tried to get it bucking again and it never did. If I recall correctly, last time it did this it was about to rain and temps were in the 80's.

have a mp, dp, n1 duals, new plugs, old fuel filter, and M2 computer.

Anyway this can be related to a bad ground (ie no ground strap?)
I recently relocated the battery to the back and that has been when the first symptoms began.

Oh, my Hawker Genesis battery is on the way out I think...doesn't hold the charge very long anymore.

 

Driving around today and the car starts bucking again!! Of course with the lights ac and fan mod on.

I put in a new ground strap since I got rid of the old one with the battery relocation.

No more bucking...so far...hope this is what fixed it.

 

No bucking today, I think the added ground strap solved my problem!