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Low vacuum and sluggish until boost.

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redliner_x

10+ Year Contributor
140
0
Feb 22, 2010
Waverly, Tennessee
My car is pulling 10hg of vacuum at idle but will idle up sometimes and run right at 18-20hg. Whenever the problem is happening the car will be super sluggish until it goes into boost and them it runs fine as long as it is in boost. When it goes into boost the wideband shows 11:1 but when the car is doing the weird stuff it shows between 18-21.9:1. I have checked for vac leaks and found none. I cannot figure out what is going on with it. Has this happened to anyone else? I didn't lots of searches but could find nothing of the sort. -Tim
 
My 91 is kinda doing the same thing. I will be driving along, say 60 mph, and then it feels like I runout of gas, wb goes dead lean, and rpms drop and the car feels like its on two cylinders. This problem is totally random and can't be reproduced. It happened to me once where I could pull over and stop and I piped the hood and jiggled some wires with no results. It clears up when I let off the gas a few times,feathering the pedal, and then it's fine. Happened a few times when I do a normal pull away from a red light too.
No codes are thrown, none stored in memory either. I have replaced coil, igniter, cas, tps, injectors, temp sensor, fuel filter. I have a spare ecu I need to socket, then I will try that. I might even replace the fuel pump too.
I have another engine on the stand almost ready, but I want to resolve this issue first.
Have you replaced your cas? Sometimes that will cause this issue. Didn't fix it for me, but might for you. That thing let's the ecu know when to spark and inject fuel. Worth a shot.
Good luck!
 
I had fuel pump trouble and wired it to run while the key is on, it is a new fp.. I put a new filter on it, and added Lucas injector cleaner and it seemed to help a little but then it went back to doing it again. I am gonna change out the wiring harness sense mine is all hacked and see if that helps.

Here is a video of what mine does. It will lean out and pull time until it hits boost then it will jump from running lean to running right.

http://youtube.com/watch?v=JIb5wTExPIc
 
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What the video does not show is how it was pulling time until it hit boost. The only way I can describe it is like there was a rubber band wrapped around the car and the more gas I try to give before boost the more time it pulls, when it hits boost the rubber band snaps and the car takes off.

In first gear if you take off normal and then floor it, the car will bog down but as soon as it builds boost it will spin the tires and take off.
 
Yes I am simulating. I was gonna change back to my stock sensor today and see if it will help. It actually started when I started simulating but I didn't put two and two together until last night.
 
Try changing the voltage the ecu sees from the 0-1 volt to the 5 volt setting. That input will accept the 5 volt setting. Do a search on ecu o2 input voltage range or using wb sensor as ecu input. I got confused as well on that. I'm running Jackal sd in open loop, so my ecu isn't looking at my o2 sensor. I think if you change the voltage, you will be happy.
You did splice the wb output to the right wire going into the ecu? That was another problem I have seen on here. Also make sure your gauge is set to gasoline and not anything else. One more thing, did you calibrate the sensor before installing?
 
The stock O2 sensor fixed the problem.. The car runs great now. To anyone who reads this thread in the future.. DON'T SIMULATE THE NARROWBAND UNLESS YOU HAVE DSMLINK!! YOUR CAR WON'T LIKE IT.

Try changing the voltage the ecu sees from the 0-1 volt to the 5 volt setting. That input will accept the 5 volt setting. Do a search on ecu o2 input voltage range or using wb sensor as ecu input. I got confused as well on that. I'm running Jackal sd in open loop, so my ecu isn't looking at my o2 sensor. I think if you change the voltage, you will be happy.
You did splice the wb output to the right wire going into the ecu? That was another problem I have seen on here. Also make sure your gauge is set to gasoline and not anything else. One more thing, did you calibrate the sensor before installing?

I put it on pin 4 like everyone else does but the car just didn't like it. I just put the stock narrowband back in and I am gonna weld in a bung. I was being lazy and tried to simulate just so I didn't have to weld in a bung. I am just gonna have to put I. The work from now on because being lazy just don't pay off.
 
Ok, now, white is correct, if it had a yellow and black wire next to it. If the white wire had a green and orange wire next to it, you had it hooked to the knock sensor.
 
The knock sensor is pin 9.. I once hard wired my knock because the connector was missing on the engine side.

Most of the problems with this car have been due to a hacked up harness. The girl who owned this car before me let her brother work on it and he clearly did not know what he was doing. I aim to get a new harness but I don't know anyone selling a good unhacked one.
 
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