1G stutter 75% of the time in/out of boost

[93AWDDSM]

So, I have this extremely annoying problem. The car struggles to accelerate most of the time. It will build full boost (14lbs) but have no power and I can feel the hesitation. When cruising and not in boost with the gauge around -10 in Hg I can feel it like hesitate and right then if I WOT it goes directly into boost but again lack of power but sometimes if I let off once or twice it will pull normal-ish. Could my o2 sensor be toast, if so I'll be replacing it shortly, also the car gets extremely bad mpg. I'm talking like 9-12 mpg without boost

I've replaced:
coil pack
spark plug and wires
pcv valve
**checked for Boost leaks

 

[Zero6391]

hmmmm any cels? maybe incorrect timing, bad tune if u have dsmlink installed, etc etc

 

[93AWDDSM]

No cels
Mechanical timing is correct
Ignition timing is 5 degree btdc

Even tried swapping ECUs to see if that was the problem. That was no luck.

No dsmlink. This car is stock

 

[Zero6391]

hmmmm well u say u got bad mpg so lets start there. there is a few more things that control fuel, like coolant temp switch, MAF sensor, maybe a stuck FPR causing too high a fuel pressure and it could even be the O2 sensor, maybe a clogged cat maybe all the injectors are sticking and not operating correctly

 

[93AWDDSM]

hmmmm well u say u got bad mpg so lets start there. there is a few more things that control fuel, like coolant temp switch, MAF sensor, maybe a stuck FPR causing too high a fuel pressure and it could even be the O2 sensor, maybe a clogged cat maybe all the injectors are sticking and not operating correctly

I noticed last night that my CTS where the 2 prongs are, are kind of able to be wiggled around which I don't think should happen. I have different injectors I could try from a donor but would have to get new seals for fuel rail to install/test them.

 

[Zero6391]

Yea give it a try or u can start with the easy stuff first like testing the maf and coolant sensor, do you happen to have a pic of the spark plugs??

 

[93AWDDSM]

I have an extra MAF that has no lower honey comb. I will test both tonight and will test the CTS. I'll try an get a video of the 2 prongs on the CTS wiggling..

I'm going to BLT...again..

These are the plugs that I recently replaced 150 miles ago

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[Zero6391]

alright yea that looks like too much fuel right there and whats your vacuum at idle? my 6 bolt sits at about 16hg, perhaps maybe u have a vacuum/boost leak somewhere on the intake manifold itself. possibly the injector o rings?

 

[93AWDDSM]

my gauge sits at 18 to 20hg when idling - I'll do another BLT but I just did one like 3 nights ago and didn't see anything but never hurts to try again. I think my exhaust leaks pre o2 are causing it maybe to run lean and the o2 reads that and is throwing fuel at it. I have a leak @ head to manifold and manifold to turbo and possibly o2 housing gasket to hot side of turbo.

 

[Zero6391]

well that's good vacuum but the leaks pre O2 might be causing all the trouble with the stuttering

 

[93AWDDSM]

well that's good vacuum but the leaks pre O2 might be causing all the trouble with the stuttering

My 2G manifold is a little old also, small hairline cracks here and there. I'll have to wait until Saturday or Sunday to change the gaskets for the exhaust. I have to drill out 1 stud for the exhaust manifold.

 

[Zero6391]

things are never easy on these cars but yea check it out and let us know what happens

 

[93AWDDSM]

things are never easy on these cars but yea check it out and let us know what happens

I'm going to BLT as well as some beer and some more testing of the CTS and potentially the o2 sensor itself tonight, possibly with more beer as well .

 

[Zero6391]

beer fixes a lot of thing and whatever beer cant fix there are hammers, famous teachings of Jeremy Clarkson

 

[93AWDDSM]

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Snapped a quick pic of the vacuum at idle - will be testing cts soon

I tested the cts with a multi meter and motor was just ran, I got .29 ohm from it. Roughly per this page it's "ok"

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[Zero6391]

hmmmm what about fuel pressure and the coolant sensor? I know if the coolant sensor messes up then the computer thinks the engine is not warming up so it just dumps extra fuel in the cylinder

 

[Zero6391]

depending on the severity of the cracks pre O2 I think that will be either THE problem or part of the problem

 

[93AWDDSM]

Not sure about fuel pressure but the CTS was @ .29 ohms when tested hot so it was "in-spec". The cracks aren't major, the major part would be leaking exhaust gaskets which are definitely more severe than any current crack on the exhaust manifold. I replaced the knock sensor (autozone...) a few months ago and now it picks up every little tick from the lifters and makes it non drive-able and was wondering if maybe I should get a OEM KS?

also the car is a ticker like no other - are there any additives that would help quiet the ticking without swapping to 3G lifters. This is a stock DD old 200k car just trying to keep it alive, not race it or boost anymore than 15lbs.

 

[Zero6391]

for the knock the sensor I heard that how tight u put it in the block will affect how sensitive to knock it is, I believe it just needs to be 10ft lbs. maybe loosen it just a tiny bit and if that don't work then either replace the sensor again or go straight to oem. as for the lifter tick I use a lucas oil stabilizer and I haven't had lifter tick, maybe give that try, only 11 bucks for a bottle

 

[93AWDDSM]

So I pulled the o2 wire while the car was running and it made no difference, as well as no CEL..

 

[richardlapalme]

I fought for years with a problem that look like that, I changed EVERYTHING, including the motor, and the problem was a collapsed flex pipe for me.
I didn't take a picture of my flex pipe, but that was only three quarter of an inch of opening. So the car lost all is power.
Since then, my car is a rocket.
Hope this help!!

 

[93AWDDSM]

Well I think I have a bigger problem if the CEL doesn't come on when the o2 sensor is pulled...Would that indicate the ecu isn't seeing anything from the o2 anyways? I drove all the way to work about 20 miles with it unplugged and no CEL. What's the best way to check if the o2 sensor plug is getting power?

 

[Zero6391]

multimeter to the signal wire, not sure if the 1g's have the obd 2 port but I was able to go to orielly's hook up the scanner and set it to datastream and you can see the o2 sensor switching back and forth not sure if there is an option at the auto stores for obd 1 read out

 

[93AWDDSM]

multimeter to the signal wire, not sure if the 1g's have the obd 2 port but I was able to go to orielly's hook up the scanner and set it to datastream and you can see the o2 sensor switching back and forth not sure if there is an option at the auto stores for obd 1 read out

nope no obd 2 port for us. I'll try the multi meter here shortly and see what I get. The thing is, even when I unplugged the sensor, it's like the ecu didn't even notice as in no CEL. So was my o2 not reporting to ecu for who knows how long?

 

[boostdawd]

I recommend doing a compression test. Just to makeep sure the engine is in good shape. You are getting too much fuel and may be pulling timing causing that hesitation.