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surging, erratic boost issues

1K views 8 replies 4 participants last post by  cmeens 
#1 ·
I wrote about a month ago with surging issues. I replaced the o2 sensors and it seemed that the problem was over. I am now noticing that I am having the same problem as before, but not nearly as dramatic as before. My boost guage is showing full boost, and if i push it too hard, I can push it to fuel cut out sometimes, but the boost is NOT consistant. I had a shop check the fuel pressure, and it shows within specs. New plugs, fuel press regualtor is supposed to be fine. I do have worn motor mounts, and am ordering new ones, everything else seems to be working fine. the car is a 97 Aero. Thanks
 
#2 ·
A bit more info. The issue seems to only be during full throttle, high boost situations. The boost seems to be fine, so Im leaning to an electrical or fuel issue. If I apply brake and full throttle, I can feel missing in one or 2 cyl. Dont know if this info helps at all
 
#3 ·
Did you happen to disconnect the battery during the O2 sensor swap? From what I've read, the ECU's boost control does need to be trained with high gear, full throttle pulls from 2000-3500 RPM or something like it.

My 98 CSE still surges into fuel cut if I punch the gas sometimes. It can be pretty violent in low gear.
 
#4 ·
Hmm too much boost, erratic boost.. sounds like an APC valve issue to me.

I can't really offer much assistance here, other than to say my car does the same thing, only problem is my speedometer gear in the trans is munched and since it has no speed sense my APC doesn't know whether to boost or not boost. :roll: Sometimes going wildly into over boost, other times it's only half boost, then other timmes it goes up to the red then sputters like a drowned politician.

If you have another APC valve around try swapping that out and also check to see if the wastgate operation seems normal.
 
#5 ·
I did disconnect the battery, but I think I have met the criteria for having set the boost back to where it needs to be. I also did go through the APC, and everything seemed to be fine with it. My fuel pressure was measured at 2.95 bar at idle, and is supposed to be fine. The speedo works fine, I dont seem to have any vacume leaks either.
 
#7 ·
harman, Im not quite sure what you were referring to. I have checked the plugs, but Im not sure how to test the DI. I also dont know what you mean with the acronym "bov". I am guessing air leaks at the manifold boost valve? I have not found any leaking lines, but I do HEAR a high pitched whine that sounds like an air leak on one of the lines, I have yet to be able to trace the source of the noise though. Thanks to eveyone for the great posts!
 
#8 ·
"BOV" would be a Blow Off Valve, it's on the aluminum upper intercooler pipe leading to the throttle body, it's plastic and looks like this. If it's faulty it can lead to boost leaks and surging in some cases.

One thing to do also would be to perform a visial inspection of the boot's and shafts on the DI cassette, I had a unit start to get tiny hairline cracks causing some missfiring, I just took some electrical tape and wrapped it around the boots to keep them from arcing against the walls.
 
#9 ·
I pulled the plug on the boost controller

I pulled the plug, and put the car into base boost. I then noticed that the car seems to be missing at base boost as well, it is just not very easy to spot unil the engine is under full load. I had one injetctor that seemed to be missing, and if i tapped it, the missing would stop, but there was no consistant issue there
 
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