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Lemons race in 3 days pls help

F

FastBrick10

New member
Joined
Jan 16, 2025
So here is the rundown we have a 93 240 we did a plus T conversion and its running on a microsquirt. It starts, idles, and will happily rev in neutral. When placed under load its down on power and wont rev out. We have been able to drive it with this issue but sometimes it just has no power and you can't even get out of first gear. Speaks to me like a fuel issue of some kind but the AFR readings are solid. We changed the fuel filter, FPR, and the high pressure pump. Did a pressure test at the rail and were reading 41psi at idle. Did a injector test and injectors were all spraying good. Timing has been checked and is right. I would post a datalog but the file type is not supported.

Symptoms:
Down on power
Will not rev out under load
Sometimes just refuses to even get out of first

Setup:
B230+T
Td04 19t on stock wastegate pressure
IPD turbo cam
30lb/hr injectors
Stock fuel system
 
possibly a dumb question, but having experienced similar symptoms on a similar Volvo [lemons race car] that was not my own how certain are you the gas tank is clean?
 
Sure sounds like fuel delivery to me, does the car shake really bad on startup? You may have a clogged filter if it's only happening under load, or a dying in-tank fuel pump. FPR maybe.

I'm assuming if this is a lemons car you've already looked at the gas tank and the sending unit to ensure there isn't a giant rust hole on top of the tank and that it's not full of nasty flakes...
 
What is vacuum like under light load, and does it build boost?
Runs smooth, no misfire?
Verify no major exhaust blockage, including stuck/locked turbo. Also intake piping.
Verify correct cam timing.
 
Good MAP readings from the microsquirt? Are the AFR readings 'too good'? I.e. it never gets out of warmup and just shows the default 14.5 (14.7?)
 
Does it still have a CAT? Is it clogged? Does the turbo spin by hand, or stuck? Was the MicroSquirt left in 10degree fixed timing mode?

To attach MS tune and log files, copy them to a temporary folder and then .zip the folder (with Windows, right click and select "Compress to..." "ZIP file"). You can attach .zip files, and pictures, less than 1MByte in size.
 
Thank you everyone for responding! Ill try to respond to everything with some more info. So it makes solid 7 pounds of boost. No cat 3in straight pipe. Brakes do not drag. The wideband gives good repeatable readings (it does actually read). Turbo has been rebuilt and no exhaust/intake clog. The car runs smooth once its started no misfires. Yes its out of fixed timing and using the table. Cam timing is correct. Yes it bucks a lot when starting. Did a compression test and all cylinders were around 170psi. Heres the current story, The car was running good when we parked it last season. Over the course of last month we swapped in a new plus T motor and redid all the wiring. We had problems getting it started and we learned that the lifter pump was not working. The connectors at the top of the pump corroded off so we hotwired the pump. We still had issues so just for a test we took out the fuel filter and put in a male to male barb fitting which did not fix it. Since then it we replaced the filter and the high pressure pump. We thought the high pressure pump burnt out because of the lifter pump not working. The tank did have some pinholes on the outside which we sealed with some JB weld but the inside of the tank is actually pretty clean aside from a stickbug that fell in. I did a pressure test before the high pressure pump and got 0 psi. I read somewhere it should be like 7psi. Im like 65 percent sure the lifter pump is bad after the pressure test I did. We also completely filled the fuel tank to see if that changed anything it didnt. We cant get a new lifter pump in time so were going to the junkyard tmrw to find something that will work. Any suggestions on a car that has a similar pump? I attached a data log on the most recent drive with some full throttle pulls and a pic. The muffler is for on road tuning lol
 

Attachments

Also the timing marks on the front plastic cover are those 10 and 20 degree BTDC marks? Or is that a 0 mark in the center. We assumed they were 10 and 20.
 
The timing cover marks on a b230 are 0 to 20btdc, 0 being to the right of the little stick out with the 10 and 20 marks unless I'm wrong. And consider putting a single high pressure pump in the tank.
 
If I understand the log right, your injectors are way too small - hitting more than 100% duty cycle when going above 3850rpm. And the AFRs seem pretty rich overall - idle of ~13, ~11.5 when accelerating up to 3850 rpm and ~11 at high rpm cruise. Am I missing something?

maxed out inj.png
 
So here's my theory because 30lb/hr injectors are the correct size for my amount of power. The car has been tuned with the suspected fuel issue. The fuel supply to the injectors is not enough so the tune is telling them to open longer to spray more fuel to get the afr right but the problem is there's not enough fuel supply to the rail so the injectors are operating at 100 percent duty cycle at 3 grand and that's why the motor won't rev out or have power. Also the fuel map is not great it needs some time in the oven
 
Last edited:
Cwazywazy said:
The timing cover marks on a b230 are 0 to 20btdc, 0 being to the right of the little stick out with the 10 and 20 marks unless I'm wrong. And consider putting a single high pressure pump in the tank.
Click to expand...
In the future yea. I don't understand the marks shouldn't 0 be all the way to the left (looking from the front) engine rotates clockwise
 
seems to my dad used a fuel pump for ford turck like 2003 once. In tank pump and deleted the one under the car and ran just single in tank pump. Believe F150 but should be many pumps that will work if you just go to a single pump. Id check fuel line make sure something didnt part way plug it.
 
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