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Cherokee budget turbo build thread

Its lower compression that what I am used to tuning. 8.8:1 is low. All my fuel management has been removed. I couldn't get the VAFC to exactly read the MAP. The map was maxed out at 0. The AFC and injectors came out today. I am putting a pump and an FMU in tomorrow.
 
I've had experience with the Apexi S-AFC and it seems the stock MAP sensor wont read any boost pressure. I've concluded it's a 1 BAR map sensor, which means it wont read anything over the the natural atmospheric pressure.

I believe Split Second sells a 2 BAR map sensor with their FTC-1 kit. I havent spoken with them, but im sure you can wire in the 2 BAR map sensor with the VAFC. With that setup you'll be able to tune anything up to ~14.5 psi of boost...

Just a little info...:looney:
 
The psc1-002 that I have came from a turbo'd yj setup($125). It has the built-in 2-bar map, but no timing control like the ftc1s.
 
gradon said:
The psc1-002 that I have came from a turbo'd yj setup($125). It has the built-in 2-bar map, but no timing control like the ftc1s.
Click to expand...

Is it $125 from split second or did you buy it used?

Also, the BTM is there to pull timing dependant on boost pressure. The biggest place where timing needs to be pulled is typically at peak torque, but the BTM wont advance the timing after peak torque, which affects power.

I've personally adjusted my base timing on my jeep by cutting off the notches in the distributor and rotating the cap some. I used a timing light as well of course.. At lower boost levels, timing isn't all that big of a deal. You could just retard the timing at the dizzy and run a little more fuel and be safe. Just make sure the AFR is good.

I've personally always hated FMUs... But they are the cheapest method
 
Last edited:
Mezzer8 said:
Is it $125 from split second or did you buy it used?

Also, the BTM is there to pull timing dependant on boost pressure. The biggest place where timing needs to be pulled is typically at peak torque, but the BTM wont advance the timing after peak torque, which affects power.

I've personally adjusted my base timing on my jeep by cutting off the notches in the distributor and rotating the cap some. I used a timing light as well of course.. At lower boost levels, timing isn't all that big of a deal. You could just retard the timing at the dizzy and run a little more fuel and be safe. Just make sure the AFR is good.

I've personally always hated FMUs... But they are the cheapest method
Click to expand...
Turning the distributor does not adjust spark timing on our jeeps. It affects injector timing. Base spark timing is set by the cps (crankshaft position sensor).
 
It's a long way out, say next season, but all looks good on your end!

The AFC would work. I had a glimer of hope that it would but FMU it will have to be.
 
The AFC is out. I already sold it. The 1 bar is failure. I got the FMU and pump all set. I may do something with my 36 lbs injectors next spring. I am also not a fan of FMU's but its doing the job. Right now there is still an overboosting creep issue I am dealing with. The internal wastegate hole was only about 5/8". I drilled it to 1" which help but didnt eliminate it. I am ordering an external wastegate.
 
Its seen 13 psi for moment. Not now with the larger hole but it will get to 10. I ordered a 38mm 6 psi external wastegate last night. That should end the BS pressure issues.
 
Boost creep is when you have a set wastegate pressure but its exceeded by not allowing enough bypass to slow the turbine down. In an internal wastegate setup the bypass is in the turbine housing so the exhaust pressure continues to build if it can not be bled off in a high enough volume.
 
CSaddict,

You may want to try closing your spark plug gap to .025-.028. Spark blow out could also be causing your boost creep. If you already have, then your new external wastegate will fix your problem. Just a thought.
Brad
 
I use a colder plug than stock without a projected tip that is gapped a .030 Its not blowing out the spark but that is a good point for people to see. The wastegate will be here Monday hopefully and I can get it on during the week. Im bleeding the FMU boost off and its still pig rich. I may need to change the disc.
 
I believe its a 12:1. I bought it used and Im bleeding it a lot and its still in the 10's. I want to say the plugs are the autolite 3923's I would have to check. Our engine builder did the research on them and said they were the best option.
 
Any new on this CS addict?
did you ever finish it with the FMU i come from the world of old school supras
and we boost ours with the rrfpr also and a msd BTM so not to far off
Let me know how this worked out
i am planning on boosting my MJ 2wd
 
This kit was sold to a kid in Florida who is still running it today. It worked out well. Fit great. The only thing I would do differently would be an AEM FIC or full stand alone.
 
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