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2 x cps = +6* timing

Dedicated forum for all things electrical... Sometimes Electrical issues can really get you stumped! Not Stroker related.
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SilverXJ
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2 x cps = +6* timing

Post by SilverXJ » October 23rd, 2011, 10:15 am

This is just a cheap and easy way to add 6* to the base timing. I had a spare know good CPS and a bad CPS. On the good CPS I redrilled the locating hole on the passenger side mount ~.5" in and then cut off the excess. I then cut off one side of the mount of the bad CPS. That was drilled and tapped for the bolts. The driver's side mount of the good CPS was marked and drilled. The cut off part was mounted to the good CPS using screws which go into the new threaded holes on the mount as well as nuts to lock them in. I used a washer to take up the space between the transmission and the offset mount.

This moved the CPS about 1/2" and added about 6* of base timing. I used a dial back style timing light and checked the timing before and after the modification. Its a bit ulgy and I could probably finished it a bit better but it works. I placed the CPS as far as it would go toward the passenger side without having to modify the bell housing.

It seems to have a bit more pickup at mid range and I haven't noticed any pinging yet. If it does I can dial it back through the AEM FIC.

Back side:
Image

Front side:
Image

Installed:
Image

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Re: 2 x cps = +6* timing

Post by jsawduste » October 30th, 2011, 2:59 pm

Silver,
I cannot believe nobody has posted about your CPS mod.

I am going to give it a shot for sure. Being OBD 1 controlled there is`nt much I can do cal. wise. Anything to crank a few degree`s of timing in has to be an improvement provided we don`t get into spark knock. The cam I am running...........Hesco`s 274/480........is advanced 4 degrees to move the powerband down a bit. So you know I can use a little timing to make up for lost cylinder pressure.

Did move IAT off the manifold and into the intake tube of the "cold air" intake. This added a little timing and a touch of pulse width by fooling the ECM into thinking the intake charge was cooler.

After running your CPS x 2 a while longer (since you posted this up) how do think your stroker runs now ?

One of my "down the road" changes is to convert to a tuneable engine management system so the cals can be mapped instead of using the the fixed OBD 1 system.

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Re: 2 x cps = +6* timing

Post by SilverXJ » October 30th, 2011, 5:50 pm

jsawduste wrote:The cam I am running...........Hesco`s 274/480........is advanced 4 degrees to move the powerband down a bit. So you know I can use a little timing to make up for lost cylinder pressure.
I'm running hesco's RVOB, advanced 4* as well. Advancing actually increases cylinder pressure.
After running your CPS x 2 a while longer (since you posted this up) how do think your stroker runs now ?
It does feel like it has more power in mid range. Its not like a knock down change, but I do notice it. No adverse side effects found either. No pinging.
One of my "down the road" changes is to convert to a tuneable engine management system so the cals can be mapped instead of using the the fixed OBD 1 system.
I don't see why you can't use a piggy back like the OBD IIs do.

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Re: 2 x cps = +6* timing

Post by jsawduste » October 31st, 2011, 2:39 pm

SilverXJ wrote:
jsawduste wrote:The cam I am running...........Hesco`s 274/480........is advanced 4 degrees to move the powerband down a bit. So you know I can use a little timing to make up for lost cylinder pressure.
I'm running hesco's RVOB, advanced 4* as well. Advancing actually increases cylinder pressure.
After running your CPS x 2 a while longer (since you posted this up) how do think your stroker runs now ?
It does feel like it has more power in mid range. Its not like a knock down change, but I do notice it. No adverse side effects found either. No pinging.
One of my "down the road" changes is to convert to a tuneable engine management system so the cals can be mapped instead of using the the fixed OBD 1 system.
I don't see why you can't use a piggy back like the OBD IIs do.
A big DUH on my part. That is why we advanced the cam to start with. Increase cylinder pressure to enhance low end.

Not familiar with piggy back OBD1 systems. Could you provide an example ?

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Re: 2 x cps = +6* timing

Post by SilverXJ » November 1st, 2011, 5:39 am

Well, there is the AEM FIC, Apexi SAFC, SpritSecond PSC1, etc. A lot of them will play with the MAP sensor input to the PCM, similar to a simple MAP adjuster. Which does work as several people use it on OBD I vehicles. Its just that you can't control closed loop operation when the PCM is primarily running from the O2 sensors, aside from setting your fuel trims to 0. But you are limited to that on most of them. The AEM unit does allow you to change the signal to the PCM for the O2 sensors, but I haven't gotten that to work correctly yet.

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Re: 2 x cps = +6* timing

Post by jsawduste » November 1st, 2011, 10:37 am

Respectably that is not a lot of tunability.

I`d rather be able to map fuel trim and spark at the very least.

Closed loop operation/tunability rather then band aiding with MAP voltage or O2 input.

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Re: 2 x cps = +6* timing

Post by gradon » November 3rd, 2011, 5:46 pm

Since closed loop is based on the 14.7:1 provided by the o2 sensor feedback, having the capability to bias the voltage(with the AEM) at any rpm and load less than the OL threshhold means that you have the ability to tune the CL map as well, instead of just zeroing the fuel trims(Split Sec, Apexi, etc). It's not a bandaid, but an awesome feature, and just a step below a full standalone unit. If you have an obd1(or 2 if you don't care about CELs), disco the temp sensor in the t-stat or use a certain value resistor inline that tricks the pcm to think that the coolant temp is lower than what it is and then you can be in OL 100% of the time and tune whatever map you want(with the SS and Apexi).

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Re: 2 x cps = +6* timing

Post by SilverXJ » November 3rd, 2011, 5:55 pm

I haven't gotten the O2 feature of the AEM FIC to work yet... it appeared to work in firmware v110, but that firmware didn't play well with the PCM and made it prety much undrivable. i'm on 4.70 now.

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Re: 2 x cps = +6* timing

Post by jsawduste » November 8th, 2011, 7:31 pm

Sliver,
how did you measure the increase in timing ? Curious as when I used a light the ECM had the timing jumping to compensate for idle speed.

Does your Apexi have the ability to read timing and you were able to compare numbers ?

Have two sensors and want to copy your write up but an curious on how you came up with your numbers.

Thanks

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Re: 2 x cps = +6* timing

Post by SilverXJ » November 9th, 2011, 5:29 am

I used a snapon dial back timing light on plug #1. It was jumping around a bit, but not enough to make it difficult to read. I don't use the Apexi anymore, but it doesn't have the ability to read timing. Nor does the AEM I have now.

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Re: 2 x cps = +6* timing

Post by carlitos » February 13th, 2012, 8:31 pm

I did this mod and it worked great for me

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Re: 2 x cps = +6* timing

Post by SilverXJ » February 14th, 2012, 4:20 am

What were your results?

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Re: 2 x cps = +6* timing

Post by carlitos » February 20th, 2012, 3:47 pm

It did exactly the same. It advanced the timing by 6 degrees and have slightly more powere

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Re: 2 x cps = +6* timing

Post by jsawduste » February 28th, 2012, 4:41 pm

Hi Silver, long time no talk.

Weather here has been good enough to bring the YJ out of winter storage. Have gone through a tank of fuel with the CPS mod and I have to say that it was a big improvement.

The Hesco 274/480 cam retarded 4 degrees (well 3.64 to be exact) really liked the extra timing. Low and mid range are without a doubt more responsive and the 5200 comes up before you know it. No ping or rattle even in a lugging situation.

Did you try the alternative method we talked about ?

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Re: 2 x cps = +6* timing

Post by SilverXJ » February 28th, 2012, 6:27 pm

I have not tried the alternative method we spoke about. I only have one good CPS on hand and I like to keep that as a spare... you know how those things like to die.

I have had my PCM reprogrammed and had 6* of timing added overall as well. So I am looking at 12* of total timing added. I should have to dial some back in the FIC though. I haven't been able to run it yet due to a bug in the tune. Its not listening to the O2 sensors and sending it full rich. Via OBD I can see the O2 saying rich and the PCM turning up the fuel trim. It doesn't run well when it gets to 11:1. Its being worked out though.

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