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LH 2.4 to Microsquirt

studmuffed

studmuffed

Member
Joined
Nov 16, 2017
Location
Va
Hey all, I'm deep into my microsquirt project right now and I have some questions.

How should I wire up the CPS? I understand that I need a pullup resistor but how to I decide which wire is signal and which is power? (Ground is obvious lol) Seems like I'm supposed to use VR- for signal and the TPSREF for power?

I'll add more questions as they come.
 
Use VR+ and VR- for the stock crank sensor. Resistor goes across those two.
Check crank signal when cranking, and you’ll know if you need to invert the wires to get a clean signal.
 
Nickagriffin said:
Thanks! That's a lot of helpful info.

I saw that they used a GM CLT sensor. Do I need one or can I use the stock bosch one?

Nick
Click to expand...

You can use the stock one, but you have to wire it differently.... and it's not that great.

A CLT sensor from a LH2.2 Volvo is super common, fit's in the same hole as a LH2.4 one, and uses the same 2-pin JPT/bosch connector. This is what a lot of people use, and it works well.

You will also have to set the temp/ohm points for whatever sensor you use. This info can be found by searching the sensors serial number.
 
Thanks for the info. I got everything wired up and my sensor seem to be reading correctly. The car starts if I give it some throttle but will die without any. I can keep it running when I hold the throttle down but it's really rough and the rpms seem to drop even if don't change how much throttle I'm giving it. I have the 60-2 wheel and I have the tooth one angle set to 84 degrees. I set it to 10 degrees fixed advance to try to rule timing out but it's still dying. I noticed the microsquirt isn't reading the wideband correctly but I didn't think that was the reason why it was dying so quickly.

I'm going to try to get it to idle tomorrow by messing with the throttle body since I got rid of the IAC.
 
Check your timing, and verify TDC. I had similar results when I had a distributor with hall sensor that was clocked 180 degrees off.
 
So I got the car running and driving decently, but I'm having some issues. It tends to cut out above 4k rpms but it doesn't up the sync-loss counter when that happens. Additionally, I was getting into boost today and it turned off all of the sudden. The transmission was still turning the engine over but the engine wasnt running at all. I coasted it to a gas station and it started right back up and I was able to drive away. I have no idea why that would be happening but if anyone has any ideas I'm all ears.
 
Check that the Basic/Load_Settings>>>RevLimiter values are OK. Also, turn off all IgnitionSettings>>>NoiseFiltering settings. Noise filtering is a poor bandaid that can cause strange alternate failures.
 
Noise filter is already off and limiter was set to 6000 rpm, fuel cut only, and spark retard mode set to progressive retard.

Does that all seem right?

Nick

bobxyz said:
Check that the Basic/Load_Settings>>>RevLimiter values are OK. Also, turn off all IgnitionSettings>>>NoiseFiltering settings. Noise filtering is a poor bandaid that can cause strange alternate failures.
Click to expand...
 
Another thing to note is that my tune is super rich, like below 10 afr in some spots. Could this be making it break up? Its hard to get the fueling adjusted at those higher rpms since it cuts out so hard.
 
If it’s that rich in areas, just select the region and decrease fueling by 5% and see what happens, then repeat until you get to where you want to be.

Also, ignition timing can have a similar effect.
 
Thanks for the advice. I reduced the fueling some but it's still happening. I think its a timing issue now but not sure how to check. I heard that one way is to set timing to fixed 10 degrees advanced and then use a timing light to make sure it's reading 10 degrees. If not, change the first tooth angle, correct? My #1 tooth angle is set to 84 degrees BTDC right now.

culberro said:
If it?s that rich in areas, just select the region and decrease fueling by 5% and see what happens, then repeat until you get to where you want to be.

Also, ignition timing can have a similar effect.
Click to expand...
 
Here's my spark table for reference. Copied it from another TB'er for a baseline.
Yt32Yni.png
 
Nickagriffin said:
I think its a timing issue now but not sure how to check. I heard that one way is to set timing to fixed 10 degrees advanced and then use a timing light to make sure it's reading 10 degrees. If not, change the first tooth angle, correct? My #1 tooth angle is set to 84 degrees BTDC right now.
Click to expand...

Check your Tooth #1 angle before messing everything up.
It's like the first thing you need to check/verify/adjust when setting up an aftermarket ECU.

Your spark table has a section with high advance that's probably causing some issues (2600-redline, 100kpa and below), overall the rest of the table looks very conservative (and this might be causing some issues).
 
One other unlikely thought - maybe the spark is jumping to the wrong plug terminal at large advances???

If you remove the blocking/positioning plug from the adjustment slot in the distributor, you could try running with the disti rotated all the way to either end of the slot and see if it makes any difference.

Can you capture a log file of the misbehavior, and post it somewhere for download (with the .msq preferably)?

Edit: Oh, also check Boost>>>BoostControl>>>OverboostProtection settings.
 
Last edited:
So I adjusted my #1 tooth angle until the timing light read 10 degrees advanced when fixed at that. I went out an tested it, but it was the same problem. I got the log this time, and I saw that my Duty Cycle spikes to like 150%... Is this my problem? I never thought it was my injectors since the AFRs never leaned out but it seems like the only thing out of wack when it happened. I'll try to get the msq file posted.

Also, there is no overboost protection (probably should be lol, thought i was running 15 lbs at max throttle but log says more like 17psi at half(ish) throttle

Oh lastly, I noticed that I never updated my AFR table so it only goes up to 100kpa despite this being a boosted car, but I didn't know if that makes a difference or not when not using the auto tune feature
 
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