Hesco CPS kit problem? RENIX 87-90 RPM problem

[Mgardiner1]

Hello all! I've been lurking for a few weeks, and thought i'd make my first post and list a problem i've been having.

I'm gathering parts to do my stroker, so far i have 4.2 crank and 4.2 rods. I've got dibs on a 92 cherokee engine that will be block and head. I'm going to try to keep everything for the RENIX injection (as i have not heard of any vast improvements from one to the other) and my wrangler is already wired for renix as that was my last engine swap (went from the 258 to 242 in my 87 wrangler). I've learned a WHOLE lot from this website already, and enjoy reading about everybody's stories.

Anywho, now on to my problem. When i did the F.I. swap in my wrangler, i used the HESCO HES8790ED crank position sensor relocation kit. I set the sensor to the recommended .010 to .015 (i think i used .013). The engine would start and idle, but wouldn't rev over 1500 RPM. After checking over several things, i set the crank position sensor at .010. I was able to get 2000 or so RPM out it. I took the sensor down to about .003, and now i get 3500 RPM out of it, but thats it. It acts almost just like a rev limiter. The tach will bounce up and down and the engine stumbles and pukes. I adjusted the sensor left and right to try different timing adv/retard settings but it didn't help. Hesco even sent me another kit to try to see if the pulley was manufactured incorrectly. It acted exactly the same.
1
Has anybody else experienced this situation or have any advice to offer? I'd love to be able to get 4500-5000 RPM out of it. Thanks!

[John]

Have you called them back after the new pulley, These guys provide thorough support? I have not used that kit so have no real info to add.
John

[Mgardiner1]

Hello John

Honestly, this situation started 2 years ago when i first did the swap. When i recieved the new crank pulley, I reported back to Hesco that the problem still existed, well they kinda signed off on it as 2 different pulley's and sensors provided exactly the same results, so they felt that it was a problem with that. They told me to keep the new pulley and both CPS sensors, and send back the old pulley.

I don't disagree with him that its not the pulley/CPS sensor setup, but i'm inclined to believe that is the problem because adjusting the gap of the sensor directly effects it. My own theory is that possibly the teeth are too wide and the air gaps between the small teeth aren't wide enough (RENIX has many more teeth then the HO engines) and it might "blend" the signal going to the ECU and it can't distinguish gap from tooth at higher RPM's, which to me would explain why a smaller sensor gap would aid in the problem. I've been tempted to try to grind the openings a bit bigger, but without a CNC machine i'd be affraid of inconsistancies and then ruining the pulley.

[Mgardiner1]

:BUMP:

Anybody else running this kit? any problems like the one i described?

[John]

i would carefully check every inch of wire and clean every connector between the sensor and computer/power circuit. Moving it closer would also generate a slightly stronger pulse. I suspect the machine work to be within tight specs. Their cps kit that I know of converts from Renix to a 94 OBDI ECU system, Is this what you have?
John

[Mgardiner1]

http://www.hesco.us/shop.asp?action=det ... catId=7902

Thats the kit that i used. Its for Renix installations in non fuel injected vehicles. I did have to lengthen the wire for the CPS sensor to reach the front pulley. Maybe i should try a different type of wire? Maybe shielded wire?

[John]

That helps a lot, That is not the kit I was thinking of. Do not know one way or the other if this has inherent issues. I would still check every inch of associated wiring/connectors.
John

[Mgardiner1]

John, just thought you might be interested. Today while i was under the hood, i cut the tie wraps that held the wire to various locations in the engine bay, and i ran it down the fuel injector harness and down behind the power steering pump. Just the relocation gave me another 500 rpms, giving me a 4000 redline. So i would imagine either lower resistance wire and/or shielded wire would help. But, i'm not going to invest much time in it as i never rev that high anyway, and the jeep is going to get a 91 harness when i swap in my stroker

[John]

Thanks, good luck with it, You might consider changing out the sensor also, they can give some problems in the area as well.
John