Shudder at constant speed
04-01-03, 12:49 AM
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Shudder at constant speed
When my car is between 3100 and 3900 rpm in any gear but 5th and im not accelerating just at a constant speed my car bucks everyonce in a while. The rpms dont change but every cpl seconds the car feels like it will lurch.
Any help would be appreciated.
Ian Welin
Any help would be appreciated.
Ian Welin
04-01-03, 04:07 AM
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Happen to replace plug wires as well? Fuel filter? Does it go away if while it bucks you press the accelerator down slightly (as if to speed up a little bit) or does it get worse?
04-01-03, 10:49 AM
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odd... the only way to figure something out of the ordenary like that my man, would be do a complete tune up and check of everything. Id check/reset the TPS as needed, check spark plugs, change out the coil packs with a freinds or something (i have like ten sets laying around so thats what id do, unless someone knows how to test them? Check the FSM at www.fc3s.org on testing coil packs, i doubt they are the problem but you dont know until you test). If the engine checks out (you should be able to feel if its the engine or the car itself ie alignment) then id check the ECU. The FSM has some information on testing the ECU as well.
When the car is just cruising at a constant speed its in closed loop (i think..... ) in which the ECU is taking measuerments from the O2 sensor and the afm i think in order to get the best gas milage. I think your car has a problem with this and starts to gimp around, check the ECU.
When the car is just cruising at a constant speed its in closed loop (i think..... ) in which the ECU is taking measuerments from the O2 sensor and the afm i think in order to get the best gas milage. I think your car has a problem with this and starts to gimp around, check the ECU.
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04-01-03, 07:12 PM
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Hmmm....maybe I'm not quite understanding the symptoms.... Well, with our older cars, the u-joints on the driveshaft wear out over time and causes a vibration while driving. As far as lurching goes, I have no idea what is happening.
04-01-03, 07:20 PM
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Its not a vibration. The time it seems to occur is when I'm cruising at about 3200 to 3700 rpm (or somewhere around there). It drives nice a smooth then suddenly it will feel like it "jumps" forward for a sec then goes to normal then a cpl secs later repeats. I just replaced the spark plugs and they needed them really badly so I'm gonna try replacing the spark wires and see what happens from there. Unfortunately I dont have any friends that I can just swap Coil packs with like Roy suggested, and they seem damn expensive. Anywho, I will start with the obvious and work from there.
Thanx for the help
Ian Welin
Thanx for the help
Ian Welin
04-01-03, 07:36 PM
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Only other suggestion I can offer is double check your AFM wires and connections. Doubtfull that is it, but I've heard of it causting similar problems, but magnifield 10X - Kinda like an intermittent crazy on/off/on/off bucking.
04-01-03, 09:47 PM
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my car does the same damn thing. at a certain rpm it surges acouple times then smoothes out....then repeats seconds later. could it have something to do with the clutch? my clutch also makes a constant noise unless the pedal is pushed in (in all gears and not in gear). im going to get some grub. ill let you guys/gals know around what rpm. thanx for any help that anyone can come up with
04-04-03, 10:24 PM
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Originally posted by monte143
\ my clutch also makes a constant noise unless the pedal is pushed in (in all gears and not in gear).
\ my clutch also makes a constant noise unless the pedal is pushed in (in all gears and not in gear).
Is it a whirring noise? If it is thats your throw out bearing going out.
04-05-03, 11:09 AM
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Even easier than adding new grounds is checking your old ones and cleaning your battery terminals. My car didn't start a couple of days ago and all i had to do was clean off the negative terminal which didn't have any corrosion or anything just needed a good scraping.
04-07-03, 10:09 AM
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Originally posted by monte143
which ones did you replace...and what gauge did you use
which ones did you replace...and what gauge did you use
Originally posted by Amur_
I got a little happy with ground wires on my NA FC, both help my alternator and to chase the 3800 stumble (which I finally did eliminate.)
Using 6-gauge automotive wire (make sure it's the multi-strand automotive wire - don't use anything else - and don't use anything smaller than 10 gauge) I installed a ground wire:
1) from the negative battery terminal to the chasis (the outer bolt holding the master fuse block in place on front of the strut tower.)
2) from the alternator's tension adjusting bolt to the battery's negative terminal.
3) to replace the ground wire on the backside of the engine (running from the tranny housing to a nut up by the wiper motor.)
4) on the ECU harness in the passenger footwell. But this was a 3800 stumble fix and may not be for you. I don't have the desc. in front of me but a write-up does appear in a few FAQs out there... Also added a ground at the air boost sensor for the 3800 fix (which was what finally nixed it.)
5) to replace the main engine ground (from behind the plugs/under the oil filter to the chassis.)
6) from the y-pipe (where your exhaust splits to go out to your mufflers) to the chassis. There's supposed to be a factory ground there, but 15 years on the road tends to nuke them.
I've read mention of people who suggest adding a wire from the alternator output to the battery's positive terminal to parallel the stock wire and make the alternator's job easier. I've asked around about this, and the general consensus was that doing this is a gamble. You risk cooking some/all of your RX-7's electrical packages/components. I've decided to not do it until I'm convinced otherwise...
You might consider adding grounding straps to the back of your car, too. I haven't, but that's because I'm willing to forgoe whatever the benefit is rather than sport attachments that I think look retarded. I don't have tassels on my coat and I'll be damned if I'll have any on my rotary rocket.
Make sure that all your connections are clean. Scrape away paint and remove any dirt or oil. Use an external tooth washer between each connector and the surface, if you can. And tighten the hell out of it. Use a spray-on enamel or good-sized dollop of di-electric grease on all the ground points to inihibit corrosion (if they start to rust they won't be as effective - my boost-sensor ground started to corrode not long after I put it in - I first noticed it when the stubmle started re-appearing! I cleaned it up and nailed it with di-electric grease and she's been fine ever since.)
I got a little happy with ground wires on my NA FC, both help my alternator and to chase the 3800 stumble (which I finally did eliminate.)
Using 6-gauge automotive wire (make sure it's the multi-strand automotive wire - don't use anything else - and don't use anything smaller than 10 gauge) I installed a ground wire:
1) from the negative battery terminal to the chasis (the outer bolt holding the master fuse block in place on front of the strut tower.)
2) from the alternator's tension adjusting bolt to the battery's negative terminal.
3) to replace the ground wire on the backside of the engine (running from the tranny housing to a nut up by the wiper motor.)
4) on the ECU harness in the passenger footwell. But this was a 3800 stumble fix and may not be for you. I don't have the desc. in front of me but a write-up does appear in a few FAQs out there... Also added a ground at the air boost sensor for the 3800 fix (which was what finally nixed it.)
5) to replace the main engine ground (from behind the plugs/under the oil filter to the chassis.)
6) from the y-pipe (where your exhaust splits to go out to your mufflers) to the chassis. There's supposed to be a factory ground there, but 15 years on the road tends to nuke them.
I've read mention of people who suggest adding a wire from the alternator output to the battery's positive terminal to parallel the stock wire and make the alternator's job easier. I've asked around about this, and the general consensus was that doing this is a gamble. You risk cooking some/all of your RX-7's electrical packages/components. I've decided to not do it until I'm convinced otherwise...
You might consider adding grounding straps to the back of your car, too. I haven't, but that's because I'm willing to forgoe whatever the benefit is rather than sport attachments that I think look retarded. I don't have tassels on my coat and I'll be damned if I'll have any on my rotary rocket.
Make sure that all your connections are clean. Scrape away paint and remove any dirt or oil. Use an external tooth washer between each connector and the surface, if you can. And tighten the hell out of it. Use a spray-on enamel or good-sized dollop of di-electric grease on all the ground points to inihibit corrosion (if they start to rust they won't be as effective - my boost-sensor ground started to corrode not long after I put it in - I first noticed it when the stubmle started re-appearing! I cleaned it up and nailed it with di-electric grease and she's been fine ever since.)
