I recently bought a '92 C4 with (now) 107k miles and as far as I know, bone stock everything. Noticed lately that it has what feels like a periodic miss. Sometimes the tach will tick upward briefly when it has "issues" -- so I'm not entirely certain it's an ignition miss, so much as something fuel related, but I'm in the process of evaluating that seperately. Performance is rather lackluster and "chuggy" overall.

I've been considering moving to a 1994 ECM & harness, as I understand that will buy me "real" sequential injection as well as flash programmability (not that I mind, since I have a PROM programmer anyway!). I'll have to look around for more info on that swap, as I know I've seen it, just can't seem to find it right now. In particular, I assume I'd have to find myself a MAF sensor, since the '92 was a year that it was conspicuously absent. I'm sure there's other pinout gotchas as well.

Getting back to the point, what's not clear to me is what to do about the ignition. It "appears" that the sensing on the opti is okay... I do get a knock sensor code, which may also be contributing to the issue. But regardless, I'd like to look into moving to something distributorless.

It surprises me that I haven't been able to find a Delteq vs. LTCC FAQ. Does anybody have any thoughts as to how much of a pain in the butt it'd be to convert over a '92? Are there any timing-customizing benefits, or is the stock computer reprogrammable enough to handle that?

Thanks for any help!


Pat

 

converting to a 94 SFI has been discussed...

However, the 92 system isn't bad, all I think you need is a tune up.

1) any codes?

2) Maintenance history? The Delco Platinum plugs SUCK. There are these little platinum pucks on the ground strap. These pucks will burn and/or fall off after as little as 30k miles. I hate these pieces of ****. I suggest NGK. I also suggest new wires, MSD or Taylor.

3) The injectors are pretty good that come with, if you want to replace, I do suggest the Ford Motorsports 24#, matched set. They are cheaper than most (about $400 for the set). I suggest the matched for the batch injection, it's more relevant to the batch vs sequential.

4) LTCC is a nice setup. It removes high voltage from the optispark. But it must stay for timing information. Depending on where you live, it may not get past smog tests... same applies for the DelTeq. MSD and DynoSpark are good options. Stay clear of the Accel unit, it just doesn't look that well put together. I have the LTCC and like it. The LTCC does have some options for timing retard for boost/NOS, which are outside the scope of the ECM.

I hope this gives you some insights on what you are dealing with.

 

Why do people always post "I've got this problem yadda yadda yadda... oh and by the way I have a code."

1. Fix the code.

2. Tuneup. Especially if "bone stock" means "original plugs, wires, fuel filter, etc."


If that doesn't solve it, then start with basic diagnosis following the procedures in the FSM. If the opti is original than it is a likely suspect.

 

The symptoms of a failing opti (codes not withstanding) are:

1) High RPM stumble

2) Hunting idle

3) General malaise

 

Thanks on the constructive responses.

I've only had the car a couple months so I don't know the full history, but the prior owner did have a receipt for a "high performance tuneup" and I also just today discovered one for "R & R Distributor and Water Pump" which one would assume means it's entirely new, which a visual check seems to confirm. Not so sure on the coil or other ignition parts.

I suspect the prior owner noticed the same issue, and whatever they "tuned up" didn't resolve the issue. But at least that rules the most labor-expensive problem out.

I've been holding off on new wires until I knew whether I'd be going stock or going with coil packs. Probably wouldn't hurt to try new wires, as those are definitely looking tired.

Thanks for the advice on injectors. I'm not sure what I'm going to do yet, but I had decent luck with Accel matched injectors on my old Mustang. They were also fairly economical. Hopefully not "too" economical.

I live in Michigan, so smog checking isn't an issue. Having lived in CA for a while, I can appreciate that!

Incidentally, most of the FSM uses the Tech 1, which I'm sure is more fully featured than my scanner (one of the Actron OBD I/II ones). I can view some streaming data, but not the stuff I really want, like timing signals, doing single-cyl dropout tests, etc. Any cheap sources for these, or any data on the protocol floating around the forums? I'll do a few searches on this too and see what comes up.

The code is the generic 43, "ESC Circuit." To answer the adroit yet probably rhetorical question of why I post the problem without fixing the code first, the answer is that it's been in the shop a couple times, and they have yet to be able to reproduce the problem. Since the symptoms occur independently of the code 43, I'm assuming they're not *directly* related. I *only* get the knock code when it's cold, and the Check Engine light goes off after ~60 seconds (not sure if it's designed that way, or if the problem goes away).

The comments on the LTCC reflect my interests in it -- primarily the ability to tweak timing, and the ability to get the expensive/wear-prone equipment out of the loop.

I'll focus on the coil and plug wires and harnesses tomorrow and see what I can find. Thanks again for the help... though with this new info on the distributor being new-ish, that definitely clears up a lot of question marks for me.

 

From my observations, I would skip the Accel injectors... their products in general don't have a good rep here.

Code 43 tells me something is amiss with the knock sensor circuit.

Do you have the Helm Factory Service Manual? Get it. It will help a ton.

LTCC does not replace the opti - it must stay behind as an optical pickup.

I love the phrase "high performance tuneup." What a crock of bull**** marketing is that?

 

Fair enough on the Accel injectors, I don't have any good data one way or the other on them, except that 1 of them was defective from the factory, but the car ran fine afterwards. I'll see what sources are available to me.

Yes, I have the factory manuals. Unfortunately the knock sensors are underneath, and given I'm in an apartment, I have no subtle way of getting under the car and whacking things, nor an assistant to hold a multimeter. The shop next door has not been able to reproduce it.

I'd just like to know if the check engine light is "supposed to" turn off after 60 seconds to clear the way for more important messages, or if that means the code is no longer a problem after 60 seconds of warmup. Since it only happens cold, for about 60 seconds, I almost wonder if it's some kind of wacky thing with a ground shared by the startup air blower or something, I don't know.

When I say "get it out of the loop," I understand it's still in there... but the cap and rotor won't have HV-related wear if there's no HV going through them.

Agreed on the "high performance tuneup" being a load of crap. I'm hoping it just means a tuneup on a high performance engine... which I'd argue the LT1 being, but I guess comparatively speaking. Otherwise it's a pretty transparent synonym for "$100 surcharge." But given the "accessibility" of the plugs, etc, it wouldn't surprise me.

I'm really looking forward to playing with some "Real" tuning of my own. Which gets me back to wondering about whether I should get the '94 harness and ECM or keep it stock and hope for the best. Batch fire just sort of bothers me on religious levels. But I guess it's no worse than a carburetor.