LdotS5

So i just got a new FD this weekend 94 R2 with 52k miles... When i get on it and im at full boost at around 5-6k rpms the car will jerk forward... It almost feels like when your going to stall how the car jerks... Im prob going to take it to KDR because they are pretty close but just wanted to know whats yous thought

4CN A1R

iTrader: (6)

is there anyway you could rig up a boost gauge. it could help better determine your problem.

and which county in pa do you live in. i am in adams county, real close to york. i might be able to help, please let me know

DaveW

Yeah, you really need to know how much boost you're getting to figure this out. Do you know what, if any, modifications (intake, exhaust, etc.) have been done to the car?
Your symptoms sound like you may be hitting fuel cut from overboosting, which is a fairly common occurence in cold weather if any significant intake or exh mods have been done.

Link to fuel-cut boost pressure post:

https://www.rx7club.com/showpost.php...8&postcount=11

LdotS5

It is boosting way too much i have a guage and it hit 16psi... My best bet is to take it to a shop i think i know it has a midpipe,intercooler, greddy compression tube, it has an after market exhaust not sure what kind, and it has an APEXi controller... Is there a way i could turn the boost down on the controller and not mess up anything else?

dgeesaman

iTrader: (7)

Definitely sounds like an overboost problem. Don't push it until you get it fixed, you might be bumping on the point of a blown motor.

You could remove the boost controller solenoid. Just make sure the lines are connected back to each other.

Dave

LdotS5

So I should basically start putting money aside for an engine cause who knows how much and hard the owner ran the car with it over boosting...Will it hurt to drive the car under low boost untill i can get it retuned

dgeesaman

iTrader: (7)

If you had it compression tested before you bought it, then you'll know if the previous owner had done damage.

You did get it compression tested right?

DaveW

Since you have a midpipe, you may need to have the wastegate ported, or add more exhaust restriction, to control the boost, even with a proper boost controller. You are likely having boost creep - that is defined as the exhaust flow overwhelming the wastegate, and once that happens no boost controller can compensate.

Since I originally made up this table, but didn't have it last night when I posted at home, I attached the boost you can run with the stock ECU without reaching fuel cut.

Definitely take it to KDR, or another reputable rotary shop.

Dave

gracer7-rx7

iTrader: (16)

Take the car over the KDR pronto and get an expert opinion. I do suggest a cat rather than a midpipe so that you have enough restriction to safely control your boost.

You are potentially in a very dangerous situation with the car boosting that much.

samad

iTrader: (1)

dude let me know what the overboost was a result of...i had the same problem with
a stock exhaust and still do with the resonated midpipe..it just gets to 16 faster now.

LdotS5

Sorry it does not have a mid pipe i meant to type downpipe... I was thinking about too much stuff when i was typing... No i didnt get the car compression tested drove 8 hours to get it i though $16,000 was cheap for a 94 R2 with 50k miles so i really wasnt worried about the engine... big mistake..

DaveW

Well, if it's driving and idling OK, it's not broken yet.

If you don't have a midpipe, it will probably just take a fix on some missing vacuum tubing, a malfunctioning solenoid, or a stuck actuator.

Just keep out of full boost, and get to KDR, etc., to fix the boost issue before you DO have an engine problem.

Dave

LdotS5

Its not the smoothest idle i ever heard but i just thought that was because it runs rich... Every time i call KDR i dont get an answer.... Ill call later and leave a message... Another thing you might be able to help me out with.. When ever i pull off and turn like at a light or stop sign i hear a clunking in the rear... on the high way i dont hear or feel it just from a stop.

Mybaby

Good luck getting him on the phone (not a bad thing).
Especially if he doesn't know you and hasn't serviced your car before.
If your not to far away head over there PRONTO, like dave says.
Dave's @KDR is a good guy and a even better mechanic.
You may have to wait around a little but he take a look (if he's not swamped) and diagnose you right.
Good luck with that.
Dave S

dgeesaman

iTrader: (7)

Where in PA are you? You may have other options: KDR is good, but it can take some time to get on the schedule.

LdotS5

Im in Pottstown, i figured out why i was hearing noise and felt so much movement in the rear... jacked the rear up and it turns out I have a posi rear end... now i just have to get to KDR for the boost issue and make sure no engine damage occured

Carpenter

Did you get the car in Greensboro?

LdotS5

Yea i ended up driving down to Greensboro