What causes an FD to bog?
 

Just when I start the car and I fully warm it up I get some bogging. The car jerks at low throttle, at around 10% in 2nd and 3rd at around 2k RMPs. I have problems when boosting. Thanks

OMFg I have the exact same problem, but my car boosts fine. To this day I still don't know what causes it. What other mods do you have?

Greddy pullies, DP, and 3" exhaust. No EGR. Stock ECU, nothing more. My other car, an eclipse, used to do the same. It was running too rich, below 10:1 AFR. I am guessing it is something fuel related, be it the injectors or fuel filter. I'll perform the basic tune up and I hope it comes back to life.

FD's are known to have this "3k hesitation" problem. It happened to me too at partial throttle when the car was just warmed up in the morning. After I installed a PFC, it was gone.

I had the same problem i thought it was because i had a large street port but i didn't have boost problems.

Mine is doing something similar. At cruise loads below 3,500-ish I've got some serious bucking. Similar to fuel starvation. I ruled out starvation when it became obvious that over 3,500 or under boost the car runs fine. I did recently remove my third failed Jacobs ignition box and return to stock ignition on my very lightly modified FD. This map seems to agree with my observations. The plugs were terribly fouled so I'll be heading over to Gotham Racing to pick up another set on the way home today to eliminate that possibility though I suspect really dirty injectors. The plugs are past-due anyhow.... :(

my car does the same thing. I always thought, that is just something that FDs do at such low rpms

Check all your grounding points. I had the same problem before I changed all the ground straps on the car. Damain has a good post w/ pictures

Funny, I was just going to say that I solved my problem by tightening the ground cables that I forgot when I had the UIM off over the weekend. If you don't have any suplimentary grounds it might be good to add one or two. The electrical system on (it seems) all RX-7's is a bit feeble after a few years have passed. I can't say for 2nd gens but on my FD and on my 84 GSL-SE adding ground cables is necessary to make up for only marginally addequate systems designed at the factory.

A little devil :devil: that lives inside almoast every FD moded or not, a lifetime resident who will never leave you car, no matter what you do, sometimes wil bug you more sometimes less.

Mine just went on vacation, to spend my latest repair bill. He'll probably be back when he's out of money.

Haha, ohh yeah he'll be back, soon or later... lol.

yeah i had the same problem with bogging before 3k solved the problem by installing hks earth link grounding kit.

wow, i think god really likes me!!!

i encountered the SAME exact problem tonight..i was gonna just post a new thread about this but thank god someone bumped this thread..

anyway, on my way home tonight, i noticed some bogging (jerking) in low rpms in any gear..well i only experienced it in 1st, 2nd and 3rd because it was in the city..

today was the FIRST day, well technically the second day to drive the FD in the rain and it wasnt even raining, it was drizzling..

anyway, car started up fine, turned on my headlights and went about my way, about 1 mile down the road, the car started to jerk in the low rpms (i was in 3rd) and i was like WHOA, whats happening??!! i get the the red light and my idle starts jumping from like 1k-2k back and forth..im like hopefully this will go away but no, 1st gear was sorta alright, shift to 2nd and try to bring the revs up but the car kept on jerking..

i pull over to the side, car idled fine (18in vaccum)..im like hmm, let me turn off all my acc, cause maybe its drawing too much volts? put it into first gear, revved to about 2500, shift into second and it started to jerk again..im like damn, i pull into the gas station and shut teh car off..opened the hood and checked all visible hoses, IC couplings, map sensor and everything seemed to be ok..

so im thinking, this is the very very first time the car ever did this after a year and a half of me owning it..could it be gounding problem as well too? after i got the car towed home, i was moving it back and forth in my driveway and it ilded fine, moved fine but i didnt really drive it yet again..

im hoping its something really simple, not like a bad fuel pump or a closed fuel injector(?) or something..

do you guys think it could be the TPS??

it sucks cause after all those months i owned this car, it happens on a day where i take the car out in the rain for the first time..i really want to rule the rain out but for some reason, as stupid as it sounds, i believe the rain has something to do with it..


EDIT: o wait, before i went to work, i put 10 bucks of gas..do you think this could happen because of wrong octane?

there was a new kid who pumped my gas and i told him 93, that pos kid prob put 91 or something..could this be a factor too??

No.

First things to check are grounds and TPS.

ok thanks, just trying to rule out alot of things that are floating around in my mind...it makes things alot easier..:)

Congratulations, you have the imfamous hesitation/bucking syndrome.

I'm guessing you have the stock ecu. I tried adjusting the tps, new plugs, wires, iat, etc. Nothing fixed it. My problem was only fixed after going to a PFC.

not to offend or tick anyone off but... i notice there's been about 4-5 reports (that I have seen) about the 2K rpm buck. i personally have it as well. every gear right at 2k rpm. But is it the same cause as the 3k? just wondering cuz the ratio of us 2k vs the common 3k is really tiny. b/c i'm perfectly find at 3K. i've been bucked like once at 3.3K but never felt it again. hehe. i dunno. i wondering if it's like a lemon sensor we have haha.

Carlos

i have this problem too, i think its the injectors. once u get a pFC it should solve it tho. i ahve the same problem so i always run with the PFC

I've had both (unfortunately). The 2k bucking seems to be so much worse than the 3k.

I had a 3k hesitation it didn't always happen but I noticed it more when the AC and lights were on. Grounding the car better definately solved the problem. I don't have any 3k hesitation and I am running the stock ecu.

However when I had the 3K hesitation it was noticable but nothing that would make me think I could not drive the car and it was not 2k it was right at 3k.

Bog Mush Hesitate Loose Power Fluff
 

Mine bogs down at seemingly random times when cruising at light loads. If I downshift and run at higher revs for a while, it seems to behave until it needs another spanking.
The problem seems to be worse when the weather is damp and dreadful.

I also have a problem of the starter randomly not kicking in the first time when the key is turned.

Both of these sound like they could be tied to the above fickle fingers of fate pointing at the grounding as the culprit.

I heard there are aftermarket grounding kits? Who/Where has them?

If the bogging is happening when you first step on the gas pedal, if you have a PFC, try changing injector decay time value.

rotaryresurrection has some..

Grounding kits
 

OK, thanks, I guess I can search on that.

I was hoping there was something available locally, but we take what we can get...

http://www.rotaryresurrection.com/ comes up out of google.
But grounding kits are not listed among his parts, and his site says:

As always, you can email your requests to me at hypntyz@charter.net. You can email the guy who purchased my parts, and should have whatever you need, at interservco@comcast.net. Other good sources for used FC parts are Rick Hawley at indyparts.net or rhawley@comcast.net, and Jonathan Greear at jgski2000@hotmail.com. IF you’re looking for electronic parts such as wiper switches, logicon units, idiot cluster lights, etc. check out Icemark’s page at www.mazdamark.com. He rebuilds all FC electronics and is highly recommended, a pleasure to deal with.

Note that I do NOT sell engine rebuild kits or parts. I get all my parts through atkins rotary, www.atkinsrotary.com. I do not sell any new or aftermarket parts for RX-7s.

So, I guess I can search where he says he buys... I'll try to remember to post if I find a kit...