Strange physical "hesitation" between certain RPM and boost levels

**Kittenpunch** · 05-03-2014, 01:36 AM

So a little background first. I picked up my 92 Stealth TT yesterday. She is immaculate, bone stock aside from a stage 2 clutch, 150000kms, pristine interior, beautiful bodywork, etc. She passed mechanical so I figured she was a steal.

HOWEVER, and this is a big however
...

She seems to have a bit of an issue between 2k and 3k rpm, and (according to my stock gauge) 0-9psi. Any time I step on it, no matter what gear I'm in and I'm between 2500 and 3500 RPMs, and as long as I'm generating under 9psi of boost, the car seems to hesitate. And I don't mean it loses power - I mean it's a full-on stuttering, as though my wheels are locking up or my clutch is suddenly engaging extremely quickly over and over again.

Now I've done some searching and the common issue was the ECS sending faulty signals to the ECU (I had the dreaded flashing tour/sport light), so I unplugged it and the stuttering still occurs. Other than the physical feeling and lack of power, the car idles fine and I don't hear any weird noises. I was thinking it could be vacuum leak, but it wouldn't make sense that the issue would disappear after making MORE boost. Then I thought maybe a wheel speed sensor was off and it would lock up the wheels thinking they were losing control (that's almost what it feels like, like when your RPMs are too low and you let your clutch out).

It's not a huge issue, because other than that the car runs fine. But I would like to be able to step on it without that hesitation. Does anyone have any ideas as to what it could be?

**Kittenpunch** · 05-03-2014, 02:04 AM

I just realized I posted this in the wrong subforum. Not sure if mods can move it or not?

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**GTOJOE** · 05-03-2014, 04:32 AM

I also had this problem and it was the fuel pump resistor. The car has a feature where it runs the fuel pump on low voltage under light load then under high load it switches over to high voltage. The problem is that it sometimes changes slowly so it suddenly gets no fuel while it changes from low power to high power. It's easy to determine and can easily be reversed.

do this

Stealth 316 - Fuel Pump Relay/Resistor Bypass

if it solves the problem you could buy another resistor and relay or leave the relay bypassed. Or you can do the full fuel pump hot wire.

Stealth 316 - Fuel Pump Re-Wire

**DK77** · 05-03-2014, 04:43 AM

That's a good place to start, I've had a similar issue as well. Also, are you reading boost from the stock gauge or do you have an aftermarket gauge? The stock one is not a very accurate indicator of boost as it just shows basically how much load the motor is seeing and not how much actual boost you are making.

**Kittenpunch** · 05-03-2014, 08:18 AM

I'll give that relay bypass a try when I get the time and I will let you beautiful people know how it turns out! And I'm reading from the stock gauge, though I know it isn't accurate. However at least I know it only seems to be happening when I'm making boost.

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**Kittenpunch** · 05-03-2014, 01:21 PM

Oh, I wanted to mention. The only light on my dash is the "anti-lock" one, and the previous owner told me that had to do with my ebrake cable or something. My speedo is also slightly off, if any of those issues make any difference.

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**GTOJOE** · 05-03-2014, 11:27 PM

ABS light could br a whole bunch of things but the handbrake cable is not one of them. Could be the ABS sensors on each hub/axle. Sometimes they get crap in them and they stop working.

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**Kittenpunch** · 05-05-2014, 01:11 PM

Alright so I did the relay bypass and it seems to be a little better so I went out and picked up another one in case the old one is on its way out. However the stutter is still present. Anyone else have any more ideas they could throw at me?

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**GTOJOE** · 05-06-2014, 07:57 AM

Try unplugging the MAF and go for a drive. It will cause a check engine light but just ignore it. If that doesn't solve it disconnect the battery to clear the CEL and plug the MAF back in.

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