Hello,

My AE has developed this odd problem of late. It starts to stutter at around 5 psi, and won't accelerate properly. Otherwise it runs perfect, even with a few psi it runs fine. As for mods it has a haltech, T04S, FMIC, tial wastegate, SR Motorsports exhaust manifold, Blitz blow-off valve and some other stuff.

Here is a list of this that have been checked and are operating correctly to the best of my knowledge:

-Had turbo checked by Saab mechanic and drag racer(neighbor), and he said everything was fine.
-Had the wastegate apart and everything seemed fine.
-The tune on the Haltech is fine. Don't know about all the sensors?
-Timing is correct.
-Fuel injectors and fuel filter are fine.

Anybody else have any ideas? I'm trying to get the car in good running order so I can sell it shortly, and I would truly appreciate the help.

-Thanks, Brian Doty

 

is it misfiring or just hesitating?

 

What happens above or below 5psi?

Does it do it at WOT and/or light throttle?

Does it continue up and throughout the powerband? (like, 10psi?)

If you're in 5th gear and you go WOT (before 2ndary injectors kick-in) and see 5psi, does it still do it?

 

i jus wanted to throw my 2 cents in real quick. might help things go a little quicker. i had an 87 TII and it did the same exact thing to me. my car was bone stock, except for a Turbo Smart V-Port BOV. like clock work if i was WOT, it would hit 5 grand and start to hesitate. (now granted my car was running at the full stock 10psi.) almost like a bump if you know what i mean. a very sudden and abrupt loss of power. each hick-up was a millisecond in duration. i never did discover the issue before i sold it to my buddy who turned around and tore it all down for a ground-up rebuild. i hope that sheds some light on what is going on!
best of luck BDoty311!!

-Smoke-

 

Its just hesistating, doesn't sound like misfiring.

And it starts at 5psi, and continues from there. Below 5 psi, it runs good. Except it runs really lein off-throttle in gear. Not sure if those two things are connected.

The amount of throttle doesn't seem to matter. I mean, obviously it takes a certain amount of throttle to spool up the large turbo, but regardless, it doesn't seem to matter.

 

check your plugs

something similar to his happened to me and my plugs were just REALLY fucked

it would boost fine, but once i hit around 5 psi the car would stutter and just NOT acceralte like it used to

once i replaced the plugs everything was fine ...

check your plug wires if your plugs are fine .. maybe its time for half a tune up?

i actually made a thread on it .. i'll try to find it to see what my exact symptoms were...

 

https://www.rx7club.com/showthread.p...ighlight=plugs

theres the thread that i made .. sounds like your issue ...

check your plugs and if they are not bad replace your wires ...

should be good

 

I've been getting high end torque loss.
The wires were worn out, and I have replace them.
That got some improvement, but there is more needed.

Thanks for the plug reminder.
I still have the plugs in from the rebuild 3K miles ago.

New plugs tonight!

 

My spark plugs are new, and my plug wires seem to be fine. I guess I'll check them out though. Could a bad coil cause it aswell?

 

The coils rarely go weak.
When they go, it's usually 100%.

Are your wires maybe the originals?
Graphite core supressor wires are only good for maybe 5 years.

 

No, they are a mismatch of two sets of aftermarket wires.

 

You can check plug wires with a cheap DMM.

I think they're supposed to be 10K ohms or less.

 

I have one, but I've yet to check the Ohms.

 

sorry for hijacking, but i have a very similar problem!

my car drives perfect when i'm not hitting boost... when i drive with "low" boost its ok, but when i smack the pedal to the metal the car is hesitating like a ****... but only in the "high" rpm range (over 3k rpm) and all the way up to redline...

i've changed my plugs already, but not the wires...

so, wires = hothothot tipp?

PS: i've also noticed a few weeks ago that there is a funny noise at my leading coil... it was licke "tick tick tick tick"... sounded to me like a spark is jumping over anywhere... i've cleaned the wires outside and it has gone away... so, my wires are fooled out?

 

New plugs and plug wires, same behavior.

It seems that I can get to 6-7psi with less throttle, but WOT it starts at around 4-5psi.

 

Check the TPS yet? Maybe there's flat spots/spikes? Not sure what kind of TPS haltech uses so sorry if you already checked that.

 

Have you checked for boost leaks? They can cause all kinds of wierd hesitation/bucking/backfiring problems. Plus they can be very intermittant and open only around certain pressures. I recommned making a boost leak tester and pressure testing the system for leaks.

 

TPS in in perfect shap (WOT reading @ 5,1Ohm)

@Bdenton

i think you mean the lines from the IC to the Throttlebody and from the IC down 2 the turbo?

nope, they are also good :/

IC also isn't leaking anywhere

but just4info...

i've cleaned my sparkplugwires this day and the stuzttering is better... i get some new NGK wires @ thursday... lets hope it solves the prob

 

Have you done a compression test? Might be low compression.

 

Yes one has been done, and its fine. I don't see how compression could have anything to do with it.

 

Car is running too rich at WOT during spool up. your a/f is probably below 10's. Check it with a wideband to see where your a/f is. Your air temp comp map could also be a factor if it does it when it because of the ambient temp warms up, your air temp comp map is probably didn't compensate enough causing it.

 

Please elaborate.

 

faulty sensor can cause rich/lean conditions due to the sensor reading the wrong temperature
it happened to my buddys FD ... it was running really rich i think ... turned out it was the temp sensor that had crapped out

 

okay, what injector time and duty cycle are you running at WOT? What was your base fuel pressure set to? How much boost are you running?

You said that the map looks fine, how do you know and what did you use to verify it?

 

For future searching users, heres what the problem was:

The gasket between an injector and the manifold was cracked and was causing a boost leak. Outside of boost, the gasket was fine and the car ran good. Boost obviously was too much for the gasket.

So boost leak.