casio

every once in awhile my car likes to do that wonderful hesitation thing. most people say it like its a normal everyday thing. i have found my car only does it when cold. is that normal? its never done it at normal temps. also, anyone know why, not only does it hesitate, but also seems to act like fuel isnt pumping right. i dunno exactly how to explain it. kinda 'stutters.'
i hardly ever experience the hesitation cause i dont lay the throttle down on my car at all when cold. so its a rarity.
and my car seems to misfire. any ideas? plugs are farely new (though experienced the ATF, but i believe my car has done this before that), wires are very new. what else should i check?

hybridracer

Want my tps? All you gotta do is order those 6 port sleeves and bring em down here, I give you da $$ AND a free TPS. Heck Ill even put it on and set it for you. Then we can check your engine and ecu grounds.

casio

tps.. tps.. wait, wasnt that supposed to be mailed out last monday? hmm. ah well, lazy ***... but yea, i'ma order them sleeves. and i'll let you help me remove the IM, port, install dem sleeves and alla that *****.

hybridracer

Heh, you gonna give me the money to ship it? I is broke homes.

casio

well, i would, but i spent all my money on your girlfriend. but i promise next paycheck i'll hit ya up with the monay!

hybridracer

Dont worry about man. Just come here and get it.

DrKillJoY

doesn't a ground strap help too.. or is that FDs only?

mrb63083

iTrader: (4)

mine does that hesitation too, but only when i run it hard for a while..

casio

explain more of this "ground strap."

mrb63083

iTrader: (4)

I remember matt telling me that it would stop after we check all my grounds...and rewire my ECU. I think that works.

thorage327

ground straps help all motors, you wouldn't believe how many older cars i've seen that someone dropped a hotrod motor in and ended up frying a shift cable, or speedo cable, or scariest of all, a melted throttle cable to a carb, do to an improper ground. for some reason, people never think about a ground strap

DrKillJoY

cut and paste from a google search :
http://www.geocities.com/motorcity/d...299/ground.htm

GROUNDING YOUR SYSTEM
There are many many problems that seem to arise with the Rx7 that people attribute to a million different things. The most common problem is the 3800 rpm hesitation, where the car suddenly hesitates, or loses power, at 3800 rpm's. This is a common problem, and no one ever seems to have an exact fix. And while I can not offer you a guaranteed fix, I can tell you that 90% of the time this is due to bad grounds. Other problems are poor idle, bad acceleration and gas mileage. All can be caused by poor grounding.

It is no secret that the Mazda RX7 is known for bad grounding in the electrical system. Mazda released a TSB for the 3rd generation 7's along with a fix by adding a second ground strap to the battery. The biggest problem with the 2nd generations is the age. So many of us have 13 year old cars that have OEM ground wires. Engines have oil and muk that has destroyed wires and connections over time. So before you begin diagnosing the problem you may be having right now, go through this list and be sure your grounds are good.

First of all, be sure the battery is good. Take it to Pep Boys, Autozone, or Parts America. They will test it for free. While you are at it, have the Alternator tested as well. With the car at idle, you should be close to 14 volts. With the lights on, the stereo on, and the brakes on, you should drop no lower than 12 volts. A bad charging system can cause a million problems.

Now make sure the terminals are clean on the battery.

Replace the negative cable. Yes, replace it. Just go to Autozone and buy a 36 or 38 inch cable. When you remove the bolt that connects the negative cable to the engine, clean all contacts. And use a wire brush on the metal surface. Purchase another ground strap, and when you replace the bolt, attach both ground wires to the engine. Attach one to the battery, and the other to the chassis of the car. Make sure any contact area has been cleaned and brushed well.

Now that we have a good alternator, battery, and now a battery to engine, and engine to chassis ground, add the following ground wires.

Main Cat- Undo one bolt on the main cat, brush the surface to clean it well, and attach a ground wire between the cat and the chassis. This will ground the 02 sensor.

Boost Sensor- Attach a small ground wire from the ground on the boost sensor to a bolt on the engine. This will make sure the boost sensor is grounded, and is the biggest cause of the 3800 rpm hesitation.

There is also a ground wire under the primary injectors, near the EGR valve. It's a pain to get to, but needs to be inspected and cleaned. I think this goes to the EGR computer. If this isn't grounded properly, you can have a host of problems.

And that's it. Now that you can be sure the car is grounded properly, you can move on to other diagnostics, and you will be confident that your work is not in vain.

hybridracer

See alan you should trust me and let me work on your car

casio

alan: matt, when can i swing by your neck of the woods?
matt: i dunno.
alan: how about monday?
matt: hmm, i dunno. i'll probably be touching myself and thinking of erika.
alan: uhhh.. tuesday?
matt: i'll be watching 'fried green tomatoes.'

i try! where are the results?!

mrb63083

iTrader: (4)

HAHAHAHAHAHAHAHAHA

Spraintz

iTrader: (1)

DrKilljoy,
would improper grounding cause hesitation in other areas of the power band and/or an overly rich situation that makes backfires and will foul plugs quickly?

Thoughts?

hybridracer

Does your car buck at all spraintz? Like on decelleration(sp?)?

hybridracer

Damnit alan, fried green tomatoes was our secret!

But seriously get your *** down here on monday. IM me and ill give you my address and you can mapquest me and call if you get lost.

Spraintz

iTrader: (1)

"buck" is kinda vague but yes, i get hesitation throughout the rpm range and if i were to leave the clutch engaged it will "buck" and on deceleration it is rough and will backfire some and then die. it will start right back up but will continue in this fashion.
occasionally it will run perfectly normal and then suddenly go right back to this.

what i've done so far:
1. new air filter
2. new fuel filter
3. installed and set a known to be good TPS
4. new O2 sensor
5. new sparkplugs
6. gutted a gross cat in case of clogged exhaust

I was gettng ECU codes including TPS until i put the "new" TPS on. now i get no codes at all.

i know compression on the engine is low but I tested it and it has a solid 75psi on each rotor face and on each rotor.

some times it will smoke if i rev it hard. kinda a greyish smoke. i'm assuming unburnt gas getting pushed out.
i get spark at all 4 plugs, the car has never been overheated, and it burns the right amount of oil.

the spark plugs will get kinda black pretty quick, not wet, just kinda black instead of that pretty tan like it used to.

when she runs right its like it always was and runs great. then it goes to doing this and i can't trust it to make it down the street.

Thats my story and why i haven't been out in it lately.

Any thought? Thanks.

hybridracer

What did you use to adjust the TPS, a volt meter or the mazda tester version which is just two LED's?

Spraintz

iTrader: (1)

tested resistance of it with a multimeter.

set it using the 2 LED's

i'm a little confused on the setting it by voltage. Ihave never been clear on where to actually test from.

something is telling me that it is not the TPS.

hybridracer

Hmmmmm does it only do this at 3800? If not you could have a clogged fuel injector(s).

Spraintz

iTrader: (1)

No, thats why i said it does it throughout all rpms.

as annoying as it is i guess thats my next step, to pull the injectors. i've been putting that off. wanted it to be something else

hybridracer

Ha yeah I understand that. Just when you take them out, I would suggest replacing the o-rings. I may or may not have had a little problem with that Basically my car almost burned to the ground, luckily no fire started though it very easily could have. I was quite lucky, ask marshall

hybridracer

Ive got some o-rings if you want em.