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Discussion Starter · #1 ·
Finnaly did the Injectors in the 234/235 hybrid so I could run a good tune ( thanks JZW) on the car. After adapting it runs well but I have a bit of stumbling on part throttle and before the car warms up.
I have good vac, get 27 lbs of boost tapering to 21 at 6000 rpm, At WOT I don;t notice any stumbling but I was not really trying to see if it was there., but when I am driving it "normally" it seems to "hesitate" as I get to 4000 rpm

The Sid shows no Miss ( if that is misfire)

I am thinking fuel so maybe the Throttle body?

Just for reference I did new plugs BCPRES7-11 gapped at .9, new Seimens 60# injectors and tune.

Prior to getting the new tune the car ran fine but way rich and not nearly as much power as when I first put the turbo on the old 235 engine.

Maybe I messed up a plug but would that show miss?, or somhow screwed up an injector? ( no leaks that I coudl see.

Any thoughts? thanks in advacne
 

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I'd hook it to a tech-2 if you have access to one, and see what's really going on. About a month ago, I was starting to get an odd intermittent stumble & hesitation, and an occasional pinging & lack of power when going to WOT quickly. A replacement air flow sensor corrected the problems, and it runs as good as ever again... GT17 "LPT" still going strong now @ 194K
 

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Discussion Starter · #3 ·
I'd hook it to a tech-2 if you have access to one, and see what's really going on. About a month ago, I was starting to get an odd intermittent stumble & hesitation, and an occasional pinging & lack of power when going to WOT quickly. A replacement air flow sensor corrected the problems, and it runs as good as ever again... GT17 "LPT" still going strong now @ 194K
Actually my thought too, jsut weird I changed ouit the injectors and plugs and now get this, but maybe its more sensitive to AFM issues now...

Thanks
 

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What are the A/F ratios when it is stumbling? I would investigate that. If you can look at fuel trims and see if it is staying in closed loop should be easy to diagnose. If it was a plug/ignition it would be more apparent at full load.
 

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Discussion Starter · #6 ·
Sounds like the MAF - I have another issue with our 9-5 - but there are MAF symtoms present as well. When I replace the headgasket I plan to replace the MAF too. If you need one to test with I THINK i have a spare laying around.
I have a spare in my ohter 9-5 thanks for the offer. But yes I am thinking the ame thing
What are the A/F ratios when it is stumbling? I would investigate that. If you can look at fuel trims and see if it is staying in closed loop should be easy to diagnose. If it was a plug/ignition it would be more apparent at full load.
Thansks I figured fule since it does not do it af WOT, I got the A/F and it is way lean 16... so off to get an MAF i guess???
 

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Start by looking at the fuel trims and airmass deviation with the tech2 before just throwing parts at it. If you have a known good AMM from any T7 car thats the best place to start. But should be able to see fuel trims and make sure the base VE mapping is close.
 

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even though the SID doesnt show any misfires, a Tech 2,, or t7suite run live though a canusb cable can tell a different story.

ive seen siemes injectors stumble before, but mostly at idle.

mike
 

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Discussion Starter · #10 ·
WOOAAH! Fix that shit ASAP.
Not driving it now, its an "extra car" for the time being

Start by looking at the fuel trims and airmass deviation with the tech2 before just throwing parts at it. If you have a known good AMM from any T7 car thats the best place to start. But should be able to see fuel trims and make sure the base VE mapping is close.
I have set up a time to get it on tech II, to see what's up.

even though the SID doesnt show any misfires, a Tech 2,, or t7suite run live though a canusb cable can tell a different story.

ive seen siemes injectors stumble before, but mostly at idle.

mike
It does stumble at idle too, but "warms up and seems ok. Ther eis idle deveiaiton form 990 to 1050 RPM. I just put in new injectors. ( maybe one is bad?)
 

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Discussion Starter · #16 ·
HMM just ran the car on TechII and everyhthing seems ok.

I am thinking its the fuel pump ( I have a walbro sitting at home) it has over 100K on it and the tech is telling me there was a buncha fautly MAF sensor that there is a Service Bulletin about it.

I am going to swap the MAF with mine from my 05, change out the Fuel pump ( its due anyways and i have one) get the wideband all set up and see if that helps at all...
 

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Discussion Starter · #19 ·
Found the issue!!!

Sorry for teh double post forgot I posted in performance:

So I posted a while back, been chasing the cause of leaning off-boost stumbling in my 2000 9=5 234/235 hybrid stage 5+. Everyone ( thank you all) said check all vac lines, did that still nothing. So today I got around to it I swapped my MAF with a "known good one" from the 03 Hirsch Aero.

It got worse, much worse.

Still figuring it was drawing air in beyond the MAF. I was thinking at the Cobra or BPV return leaking so I blew into the intake bellows downstream from the MAF and heard a hiss, it did not hold pressure... ahah! a leak.

I tried the same on the donor car and it was solid.., no leak

SO I pulled the bellows and found this!!!



Turned it over and Eureaka!



It was in the curve part of the compressed bellows, so it must have got worse when I F'd with it to get the new one in there and it was ok when curved. I had a similar issue with a split hose at the BPC one time so I was suspecting something wierd like this...

If may have gotten slapped when the serp belt went way back, but who knows?

Need to get a new one tomorrow and see how she runs, never been right since I put the engine in last year.
 
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