Hot rodding a RENIX in Cali

[cruiser54]

Absolutely normal. That black tar crap gave us fits when these rigs were new, and lots of important low voltage signals from sensors need to travel to the ECU through this connector, along with critical signals back to the injectors etc from the ECU. Basically the C101 is the roadblock on the information superhighway between your engine and the ECU.. I doubt that crappy connection has improved with age.
Alex, thanks for the photos. Perhaps now some of the "doubting Thomases" will be more inclined to believe that the refreshing of the C101 is a worthwhile endeavor.

 

[Alex E]

So I've been driving the Jeep since last night and so far it seems to nice. Obviously I dont really notice a power increase BUT I do notice that throttle input seems more precise and a little bit of the boggyness is gone. Mainly it feels like the TPS signal is cleaned up and the computer gives better fuel and timing. Another thing I noticed for sure is when I start it up, especially on a cold start, the IAC doesnt race to 2 grand then hang there for 5-10 seconds and slowly fall, it just goes to about 180 then immidiately goes below 1000. I should have tested for voltage drops before I cleaned it but oh well, hopefully Im being objective and its not just the" placebo effect".

 

[87manche]

Absolutely normal.

+1
Check out the back of the fuse block sometime too....

or not if you're terrified.

So I've been driving the Jeep since last night and so far it seems to nice. Obviously I dont really notice a power increase BUT I do notice that throttle input seems more precise and a little bit of the boggyness is gone. Mainly it feels like the TPS signal is cleaned up and the computer gives better fuel and timing. Another thing I noticed for sure is when I start it up, especially on a cold start, the IAC doesnt race to 2 grand then hang there for 5-10 seconds and slowly fall, it just goes to about 180 then immidiately goes below 1000. I should have tested for voltage drops before I cleaned it but oh well, hopefully Im being objective and its not just the" placebo effect".

it's very possible that your IAC and TPS now work better. Now that you've cleaned up your connector you may want to readjust the TPS, as removing the resistance may have changed the reference voltage level at the TPS. I mean since you're tweaking....

see the lunghd site for a good writeup on the TPS procedure. Make sure you're doing the right one, 5spd and auto are reversed.

 

[Alex E]

Whats the deal with the fuse panel? More voltage drops, I was thinking of checking PCM power and ground to make sure there isnt any issues either. Its just odd becuase my Jeep more or less runs great except for it feels like its driving in a head wind all the time. Mine is a manual but luckly my fuse panel hasent rotted out from a leaking clutch master cylinder. I cant imagine what the humidity has done over the years though.

 

[cruiser54]

Are you planning on grabbing a 90 ECU? If so, be sure to clean and tighten the connectors in the harness when you do.

 

[bcmaxx]

Hate to butt in, but is this a proven gain? even over an 89 ecu? thanks. gasket matching,cc'ing, and polishing did very little for any performance or power gains on my 89 renix head

 

[cruiser54]

It's not huge, but noticeable. Mostly in responsiveness and driveability as the ECU programming matured. 88 was better than 87, 89 was better than 88, 90 was better than 89.
After the Renix head mods did you do anything with the injectors or throttle body size?

 

[Alex E]

So I picked up a 90' ECU yesterday and installed it. Not sure how much of a difference I noticed. In all honesty I want to say cleaning C101 made a bigger difference, as it should, ASSUMING sensor signals were leaking voltage across to each other AND/OR there was high resistance that dropped voltage going to the ECU. The other thing I was thinking was...I wonder if in the past if my ECU ever went bad maybe it could have been replaced already? Either way I will say one thing, when below 2,000 rpms the engine is less boggy, it will just pull slowly til you get to a useful power band. Seems like the ignition timing is more "in sync" or better calculated now. Going up a hill or over pass, especially with people in the car seems to be the biggest change of all. I will have to say the over all drive ability is improved a lot, I will get a better idea after I drive the Jeep through different conditions, loads and altitudes to see how much of a change there really is.

Does anyone know how to cross reference the numbers on the ECU to find out a production date?

Also, what mild street cams are there for computer controlled applications, any recommendations?

 

[cruiser54]

Have you indexed your distributor yet, and verified that your sync generator inside it is functioning?

 

[Alex E]

Have you indexed your distributor yet, and verified that your sync generator inside it is functioning?

Yeah, according to the TSB correct? Where you put the rotor .020 past number 1 and all that crap? If the sync generator is functioning or not what problems would I have? I believe I've verified its function with a scan tool at some point but I'll have to check again.

 

[cruiser54]

The sync generator not functioning makes it so the injectores don't fire sequentually but batch-fire. Glad to see you've done these things.
I forget. Did you eliminate the "crush" in your exhaust downpipe?

 

[Alex E]

The sync generator not functioning makes it so the injectores don't fire sequentually but batch-fire. Glad to see you've done these things.
I forget. Did you eliminate the "crush" in your exhaust downpipe?

I have not, I was actually at my buddys shop yesterday talking about that. I want to just redo the entire exhaust system, I run a Flowmaster and everything else stock, any ideas how to run the piping in the back? I didn't know if I wanted a tail pipe still or some sort of dump, I don't want a dump because the noise but it would be nice not having to go over the axle and by the leaf spring.

Any thoughts on these products?

http://www.strokedjeep.com/renix t-body.html

http://www.precisionautoinjectors.c...6AB746F.qscstrfrnt04?productId=7&categoryId=3

Should I check for signal coming off the wiring for the "sync" signal? Is it a 3 wire connector, I can probably check it with hertz or duty cycle right?

 

[gradon]

I had Jeff Leigh bore my eliminator tb and my m3 tb as well(64 to 68.5mm). He does good work, is reasonably priced, and the turn around is fast.

 

[Mike1331]

went to the pnp yesterday and outa 15xj's not a single was a 90. scored some good looking injectors though.

buy from those two links you posted, you won't regret it.

 

[Alex E]

Cool, I think I'll order them up! I'm going to pull my engine this month and have it rebuilt, I still need advice on a cam! lol I'm not sure what to think, I might just stick to stock BUT I am definitely doing injectors, throttle body, fix my exhaust (especially the pinched down pipe thats everyone talks about) the only thing I'm on the fence about spending money on is...header, cam and roller rockers...

 

[cruiser54]

I have not, I was actually at my buddys shop yesterday talking about that. I want to just redo the entire exhaust system, I run a Flowmaster and everything else stock, any ideas how to run the piping in the back? I didn't know if I wanted a tail pipe still or some sort of dump, I don't want a dump because the noise but it would be nice not having to go over the axle and by the leaf spring.

Any thoughts on these products?

http://www.strokedjeep.com/renix%20t-body.html

http://www.precisionautoinjectors.c...6AB746F.qscstrfrnt04?productId=7&categoryId=3

Should I check for signal coming off the wiring for the "sync" signal? Is it a 3 wire connector, I can probably check it with hertz or duty cycle right?

If you have a 3" or better lift, youcan just duplicate the routing of the existing downpipe and have the muffler shop make you one without the "crush". No lift? Have them swoop the headpipe back sooner and with two 45* angles instead of the 90* angle and you'll clear the front driveshaft just fine.

Gradon is spot on about www.strokedjeep.com and his bored throttle bodies. I've installed 2 on my personal Jeeps and I'm getting ready to order up another for my son-in-law's project. No wiating. He sends you one already bored and you send him your old one. Fast turn-around. You'll like it.

I've also used Precision Auto Injectors in 2 of my Jeeps and will use a set in the project soon.

 

[Alex E]

Did you notice good improvments with each of those modifications. Do you loose any low end grunt with the t body? Except for the exhaust, will the injectors and t body effect my emissions?

 

[cruiser54]

I did the upgrades one by one just to see how they worked. I lost NO bottom end, and gained noticeable throttle response.. Heck, the 60mm TB is only 2mm bigger than an HO. I wouldn't think the emissions would be affected negatively. If anything the newer style flow matched injectors should improve emissions.

 

[Alex E]

Cleaned up some more connectors today and some grounds, call me crazy but I think when I pull the engine I'll clean up my entire engine compartment. I want to do a once over for any problem areas. Does any one have experience with cams?

 

[Johnnie Walker]

Depending on the muffler, running a turndown isn't much louder than running a pipe back. IF you like I can record a clip of my exhaust with new magnaflow and turndown.