No spark

Gunny87

Active Member
Nov 29, 2015
47
7
28
56
Murray Utah
So 3 weeks ago I pull my perfectly running 87 GT with a new engine (less than 700 miles since installed) into the garage and swapped out the 19 lbs injectors for 24's removed the upper intake pulled the fuel rails swap them over put it all back together tried starting and now NO SPARK pulled it back apart checked all the wiring, not seeing anything wrong, change the coil and TFI module still no spark!
Now before everyone goes nuts about pulling codes mine has a Microsquirt ECU and I'm not sure how to get codes from it. All I change in the program was the injector size but when I plugged it into the car the Vac/Boost gauge is maxed out and red and when it's cranking the spark cut tab is also red! I'm really hoping someone can help me get this figured out! I'm at a loss with the Microsquirt.
 
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Blown88GT

Founding Member
Nov 13, 1999
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1. Did you forget to attach the vacuum line to the upper intake?
2. Did a wire get pinched between the upper & lower?
3. After you changed the injector settings in TS, does it show online when the ignition is on?
4. There are no "codes" in the Microsquirt, you can capture a datalog (msl file) & post it here along with the msq file.

Notice that the bold text below is hidden from you post above.
Just notice it when I cut & pasted the text here. Always proofread what you have written.
Vac/Boost gauge is maxed out and red and when it's cranking the spark cut tab is also red!

This is a clue, but I don't know what it means. I don't even know what the spark cut tab is.
I think you mean the spark cut indicator.

You've changed some other setting besides injector size.
 
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Gunny87

Active Member
Nov 29, 2015
47
7
28
56
Murray Utah
this is the screen when the key was on, the spark cut tab is the 3rd over from the right on the bottom row and it went red when I was cranking it.
All vacuum lines were attached, took it all back apart and made sure no wires were pinch, and yes TS showed on line.
 

Attachments

Gunny87

Active Member
Nov 29, 2015
47
7
28
56
Murray Utah
I wonder if it could be the POS GM 3 bar BAP sensor causing this?
The front cover plate that the wires plug into fell off when it got bumped as I was doing the engine swap a few months ago but it still worked however it may have gotten bumped again as I was messing with the upper intake. I did check my wire connections and made sure they had not come apart, can anyone tell me what model and year GM vehicle to tell the part store to get a new one if this is the problem?
 

a91what

SendMeUrDataLog
Mod Dude
Apr 6, 2011
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Please post a datalog of the vehicle cranking and the entire ts project folder. I will proofread the tune and make sure it's not a setting or some such. The datalog will let me see what's happening.

If the map sensor has gone bad and shorted or filled with some kind of fluid and it reads full pressure then it's likely that the spark cut is from an overboost protection field.
 

Gunny87

Active Member
Nov 29, 2015
47
7
28
56
Murray Utah
update, the map sensor is bad, one of the wires broke off on the backside of the front panel, had my son order one trough his work (he works at a Big O Tire) using the old one to reference from, got a new one that was supposed to be the same style but in a different brand, he hooked it up today while I was at work, the car started but ran bad, so when I got home and he is now gone to class so can't ask what the part number is, I hooked up the laptop and it now reads 20 psi key on engine off and really does run awful! I data logged it but can't get it to attach to send it to you?

Can someone please tell me what the correct map sensor is so I can get the right one?
 

Gunny87

Active Member
Nov 29, 2015
47
7
28
56
Murray Utah
OK so this issue is now solved, after buying 2 wrong ones from O'Reilly's I found one on Amazon for cheep that works
View: https://www.amazon.com/Sensor-12223861-16040749-12223749-VARIOUS/dp/B01N2VHFU9/ref=sr_1_1?keywords=CBK+3+Bar+Map+Sensor+Kit+3bar+12223861+16040749+12223749+for+Various+GM+Models&qid=1580565269&s=automotive&sr=1-1

I also ordered one from EFI Source which is where the I got the original one from (since I wasn't sure the Amazon one would work) that I will keep so I'll have a backup.