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Old 12-09-2019, 01:34 PM   #1
rb92673
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Default Huge boost increase and super rich

I just got back from racing Lemons in Sonoma and have a problem I cannot figure out.

We raced Buttonwillow in September and car ran very well, it maxed out about 12-13 PSI with the stock actuator T3/T4 turbo. It would build to 10:1 AFR as it reached max boost. We did have problems with the turbo studs/nuts backing off on the 89+ manifold and eventually two busted. I had another 89+ manifold and had Yoshifab do the conversion service for T3. I did swap LH 2.2 distributors, but I did not change anything else on the car. It is running Microsquirt and I did not change the tune.

When we started at Sonoma Saturday morning, it was raining hard so we were short shifting. When it started drying up, one of my drivers said it was boosting to 20 psi and would not rev past about 4500 RPM. Sure enough when I got in it, it was boosting way faster than normal and going to full rich on the AFR gauge. I confirmed the boost readings from the MAP sensor.

Thinking wastegate flapper was stuck closed or actuator wasn't working, I wired the wastegate flapper open. I did not notice any change, it still was at 20 psi by 4500 RPM. I am going to take the wastegate off later this week to see if I notice anything.

Any suggestions on other things to look for?

B230FT in 745
T04E 50 trim
2.5" exhaust
no cat
single muffler
DEKA 80# injectors
Walbro HP pump in tank
pretty much everything else stock except for microsquirt using LH2.2 dizzy
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Old 12-09-2019, 02:44 PM   #2
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Screwed up FPR acting like a rising rate under lots of boost?

Not sure what to say about the turbo still making too much boost with the WG wired open. It can't really be an undersized WG if it was working properly to control boost earlier on.

Maybe it's an odd side effect of the rich spike - a bunch of fuel getting dumped into the exhaust and making so much volume that it overwhelmed the WG? Sort of like an anti-lag effect, only at WOT.
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Old 12-09-2019, 03:45 PM   #3
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Screwed up FPR acting like a rising rate under lots of boost?
Maybe. I plumbed in a fuel pressure sensor, but have not connected it to MS for logging yet. I have a Raspberry PI in the car and fully logged the weekend. FPR is fairly new, but who knows. I should have a spare FPR anyways.

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Not sure what to say about the turbo still making too much boost with the WG wired open. It can't really be an undersized WG if it was working properly to control boost earlier on.

Maybe it's an odd side effect of the rich spike - a bunch of fuel getting dumped into the exhaust and making so much volume that it overwhelmed the WG? Sort of like an anti-lag effect, only at WOT.
That was one theory tossed around. Thanks for the suggestions.

One thing I forgot to mention was idling is very rough now and it will die if you don't feather the throttle.
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Old 12-09-2019, 04:04 PM   #4
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Check the fuel pressure, check for a leaking injector, do a compression test. Sounds like it's still running rich.
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Old 12-09-2019, 04:08 PM   #5
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no power and additional boost? is the timing correct?
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Old 12-09-2019, 04:57 PM   #6
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no power and additional boost? is the timing correct?
I set the timing in Tunerstudio at a fixed 10 degrees and verified it with a gun. Then I set it to go back to the table the dyno tuner built.
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Old 12-09-2019, 05:00 PM   #7
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Check the fuel pressure, check for a leaking injector, do a compression test. Sounds like it's still running rich.
Didn't think of leaking injector or compression test. Injectors have two races on them, but certainly new parts fail. I got them from a known source too, not ebay.
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Old 12-09-2019, 05:01 PM   #8
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may want to verify that the timing isn't drifting with RPM, can do this in neutral with fixed timing set, rev it up as high as you can and watch the timing mark.
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Old 12-09-2019, 05:11 PM   #9
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may want to verify that the timing isn't drifting with RPM, can do this in neutral with fixed timing set, rev it up as high as you can and watch the timing mark.
I did do that and it was stable to probably 3000 rpm. Go higher?
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Old 12-09-2019, 07:13 PM   #10
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if nothing else works, I'd check that. 3k with stable spark tho is probably pretty good.
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Old 12-09-2019, 08:19 PM   #11
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Rag, or something else, plugging up the exhaust?
What do the plugs look like?
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Old 12-09-2019, 09:05 PM   #12
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Rag, or something else, plugging up the exhaust?
What do the plugs look like?
Maybe I blew out the muffler, it will be on the list of things to check. I pulled one plug and it looked carbon fouled and sooty. Not damaged, wet or oily.
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Old 12-10-2019, 07:22 AM   #13
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The 20 psi has to be something with the waste gate I would think. Plugged exhaust would restrict boost. As far as too rich, I've had the injector drivers on my microsquirt fail and dump fuel but like 6 gals in a couple minutes. I have big injectors though too, close to stock might take longer to empty the tank
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Old 12-10-2019, 10:01 AM   #14
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The 20 psi has to be something with the waste gate I would think. Plugged exhaust would restrict boost. As far as too rich, I've had the injector drivers on my microsquirt fail and dump fuel but like 6 gals in a couple minutes. I have big injectors though too, close to stock might take longer to empty the tank
I am going to take apart the wastegate. We ran the car under this condition for two days and our fuel consumption was normal, about 7 gallons an hour in the dry.

I appreciate all the comments and suggestions from everyone.
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Old 01-29-2020, 08:13 PM   #15
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Checked ignition at idle and timing belt, both are correct.

Removed and checked wastegate, did not see any issues.

Checked compression with engine cold and dry 80 110 110 110. Then connected compressed air to each cylinder at TDC and I can hear air escaping, but it is most noticeable on cylinder #1. It sounds like it is leaking out the exhaust on #1.

No air in water, no frothy oil. I did have to add about a gallon of water to the cooling system, but I think my last driver was driving the piss out of it and it started overheating in the long line to get back to our pit. I checked the logs and it was a solid 180 degrees for his 1 hour stint

I don't understand how a leaking valve could cause extra boost though.

Still need to check injectors and timing at higher RPMs.
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Old 01-29-2020, 09:28 PM   #16
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Sounds like boost but no airflo, ms runs fuel off boost so if no flo would give tons of boost and tons of fuel but no power, maybe something in the intake or issue with cam
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Old 01-29-2020, 09:29 PM   #17
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20psi with gate open is new tho
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Old 01-29-2020, 09:49 PM   #18
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20psi with gate open is new tho
Unless the wastegate is very poorly designed it shouldn't make full boost anywhere near normal RPM, if at all when the flap is open.
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Old 01-29-2020, 10:20 PM   #19
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It is the 5 bolt garret wastegate that was attached to the stock T3 before I upgraded to a T04e.
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Old 01-31-2020, 06:28 PM   #20
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Pulled the head and #1 exhaust valve is burnt.



I am thinking that might be the problem. Sent head to machine shop for rebuild.
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Old 03-02-2020, 01:55 PM   #21
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So I had the head rebuilt. We raced Lemons last weekend at Inde Motorsports Park in Willcox, AZ.

Once back on the car, it was running very rich so I tuned what I could in the garage and then ran Tunerstudio VEAL for the first 30 minutes of the race. Boost was back to normal at ~12PSI.

The only thing I can correlate the large boost increase to is the burnt valve and the overly rich VE map.
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