ok, iv been reading as much as possible on here about upgrading the computer and chips in the CCQETS.....when i first started my 350 swap in the spring everyone i talked to said that it was a waste of cash...but now it seems like everone is doing it. i have a 84 TA with the stock qjet, bolted onto a 350. im having some isues in the high RPM area and a few of my smart race buddies keep saying "i dont see how you can gain 52 cubic inches (357ci) and be able to keep the stock computer..."..and to tell you the truth,....i dont either, can someone explain that? i also noticed that peoople keep talking about L69 chips and computers are better for the bigger motor swaps, and cams that people keep doing, and that the ZZ4 is for a higher compression engine and to bypass the EGR. everyone said "ohh ill let you know what happens!!"...but they never did. iv found a computer off a 84 L69, and 87&88 monte LG4's. they are all 40 bucks, but i dont know what to get if any...any help?

 

Just a disclaimer, I ordered those parts before I said something to that effect and I still haven't gotten them. SDPC said that GM didn't have that chip (the one that comes with the ZZ4 kit for later LG4's) in stock, and that they were going to try and find another dealer that has them in stock. Supposedly the sales rep found it at another dealer, but they wouldn't ship it to him because it's a performance part. Supposedly he's still trying to find someone to get it from. So I dunno.

 

First,
The probable reason why you are having high rpm problems is fuel related - as in not having enough. If you have a block pump, ditch it and get an in-line electric and put it right near the tank - regulate it to 5psi. You also will have to richen the secondaries in order to maintain the proper a/f ratio at WOT.

Second,
Typically an injected car wouldn't run correctly if you went from 305 to 350ci because the computer (PROM chip) would never be able to handle it - it would go into "safe mode". But because the LG4/L69 computers only control TC lockup, distributor curve, and part-throttle a/f ratios (not counting other sensors/systems), it can adapt to a larger motor with minimal problems. In fact some cars run better with larger motors because the factory was not that great in programming PROMS for any car (thanx GM). The worst thing that could happen is the primary side being too lean where the computer can't regulate the proper a/f ratio. I will be honest - at over 375hp, I never had to do the primary side reichening and the car runs fine - actually it runs a tad rich (ok for everyday use). I would think a 383 or 406 would need some primary work to run good at part-throttle. You only need to adjust the secondary side for optimal a/f ratio with different metering rods and hangars. A good a/f guage like the Edelbrock is the only way to get a good a/f ratio (wide band is definitely better, but more $).

Now at least in terms of what I and a few others have worked against, there are only a few things that would affect the car enough to not make it run decent (or better):

If the engine vacuum level is too low (big cam or vacuum leaks)

Not enough fuel/fuel pressure (makes car lean out)


Compression shouldn't matter unless there is detonation (some LG4s had knock sensors - all L69s should have them)

Cubic inches shouldn't matter as long as there is enough fuel at part and full throttle to sustain the motor. I think you could run a big block with a stock computer (carb, distributor, and sensors too) becuase there is no particular item that can't be moved around - at least in theory (in my demented mind anyway).

Help you out at all?

 

see thats what i thought, and have been told about the computers. since it was the first few years for them on our cars, they dont control alot, so you can beef up your engine without a problem. iv dumped a few hundred bucks into my car trying to fix this damn stumble..one of my friends calls is a hicup... all new ignition crap, new fuel pump (mechanical), fliter, lines.....got my timing set at 20 without knock....iv got a B hanger and DR rods..did all the performance q jet stuff (AV flap, and all that)..and it still stumbles. the only thing that seemed to help it at all was bumping my timing up from 12 to 20, and i dont know how much more timing shes got in her...i was hoping that the distibutor curve in the other ECM's would maybe solve my problem...but then again its a long shot..... also the mechanical pump i got is suposed to be good to 9psi...and i was told that Qjet only needs 3psi to operate .

 

I have read that you shouldnt run a pump that puts out over 6 psi to the cc quadrajets. I have also read that some people used the block pump with a low pressure inline electric pump near the tank to keep fuel to the mechanical.

Ben

 

my new pump is a OEM pump from napa. the guy behind the counter said 9psi...but it could be 6

 

i just found a 87 monte carlo SS ecm for 10 bucks...im thinkin about tryin it. are all the connections the same? and since i have a non knock sensor LG4, will it be throwing codes?

 

I think that the computer will work, but you would need a new prom for sure. The comp probably wouldnt be to happy if it wasnt getting all of the info that the chip expects. Here is the part number for the chip you would need 24502457. I got that from this page: https://www.spoperformanceparts.com/...119&CATID=1099 It has part numbers for a bunch of stuff for a computer controlled carb 350 swap. If you go www.gmpartsdirect.com you can put in that part number and it will give you a price of $65. I believe that the computer would work with that chip because I was told that the computer listed on my first link was just a stock 87 l69 computer, but that chip is for a 350 H.O. without knock sensor.

Ben

 

sweet!!, alright thanks for the part number. anyone else have any advise?? im surprised we havent heard from Five7kid!! where ya at bro? this all sound good to you?


also...how much of a curve will this put on my ignition? more low end, more high end?? im just curious to what exactly it will do.


another thing...im not gonna have to burn anyhting onto that chip am i?

 

You will not have to burn anything. It is a chip designed by gm to work with a high output 350 using the computer controlled carb setup out of a thirdgen. I think it was made with the zz4 crate motor in mind, but has been used by quite a few people with other 350's and such. It should definately have a better spark curve than your ol lg4 and it was designed with the larger cubes in mind.

Ben

 

FYI I scanned in the instruction manual for that 350HO kit, and put links to it in this thread. The manual is much more informative than any of the product descriptions.

 

alright guys thanks alot for the help!! im wondering if this will help out my 13mpg issue as well...and ther eare diffeances in the 84 L69 computers to the 87's?? just in case i cant get this 87 l69 one, im looking for a backup..any other cars have this motor in them?

 

dont know if you all know about this page or not, but here it is anyways GMECM

 

Having done a couple of these I'll chime in......

Paul is right on all counts. The stock setup is AMAZINGLY adaptable. A carb is 90% self-adjusting to begin with, unlike a fuel injector. Remember carbs have been matching fuel with air for ver 100 years, no computers necessary. The ECM's control of the carb is for "fine tuning" not total outright control of fuel flow. That's why changing the chip isn't strictly necessary when changing the engine's displacement. I have found this system very forgiving of some pretty wild cams, too.

If you have an LG-4 in your car right now, it' not unusul to be able to crank up the timing quite a bit and get more power. BUT the programming gives it a very LAZY timing advance RATE (relative to RPMs). This is where an aftermarket chip helps an LG-4 computer out a LOT. You can gain substantial low-end torque. But you don't need the GM chip specifically- ALL aftermarket off-the-shelf chips will bring the advance in much quicker than stock LG-4 programming. Hypertech, Fastchips, etc, etc. There is nothing magical about the GM chip that I am aware of.

Also note that when setting your timing it is IMPERATIVE that you disconnect the 4-wire connector that comes out the back of the distributor to thw wiring harness going over the trans bellhousing. This supplies the distributor with it's timing signal and disconnecting it takes timing back to zero, so you can set your initial timing correctly. 0* is spec on an LG-4. I've gone a high as 8* BTDC on a stock LG-4 (1985 vintage, 9.5:1 compression) with no detonation and increased performance. Any higher and it runs slower, even though it doesn't always set off the knock sensor for some reason.

If you are using an aftermarket chip this all goes out the window, however. It depends on how much timing the chip burner programs into it how far you can set your initial timing. I doubt you could over-advance the timing that far on an aftermarket chip as you can with the stock LG-4 one.

In any case, if you have a stumble or other drivabilty problem chip programming will not fix it 99.9% of the time. It can help make some power in some cases, but it won't fi drivability problems like it often will on an EFI engine.

 

i never messed with the timing on the LG4 at all cause i was gonna put the 350 in its place. the timing on the 350 is set to 20 btdc. i cant figure out what my problem is, so im just doing anything possible basicly....i mean youd think that it would be a gas/air thing...but i took care of all that already..on of my friends descrbed it as "its almost like the computer is shutting your carb of for half a second....then turns it back on." which i know isnt the case...but ohh well im gonna do the ecm swap casue it will help out in the long run anyways. also,, what chip do you recomemd damon? the GM chip is only 65 bucks......


also the only other thing i can think of is to rebuild the carb...then after that im out of guesses.

 

Well, if the GM chip's only $65 then why not? That's probably less than an aftermarket one, I bet.

Get a scan tool and look at things the way the ECM sees them. Diagnosing computer controlled stuff without a scan tool is a guessing game. You could throw parts at it for weeks and never hit it.

 

wouldnt my check engine light be on if it was throwing codes though?? i havent got that light to come on yet except when im doing my timing.

 

well i just put a scanner on my car and all i got was the code 12 , so everything is operating fine according to that.

 

The computer that runs the carbureted motor is pretty "stupid." Stuff has to be fairly far out of whack before it'll throw a code. You want to watch what the computer is seeing real-time and try to deduce what is going on. It may not point you in exactly the right palce but it might give you some solid clues.

 

alright...chip has to be "special ordered".... what will happen if i jus hooked up the stock 87 l69 computer till i got the chip? would it run fine...better than the stock lg4?

 

I would think you would be better off with the lg4 chip until you could get the other being as the l69 chip was designed to work with different sensors and such(mainly the knock sensor) How long is it supposed to be before you can get the chip from gm.

Ben

 

i dont know.. i ordered it through GMpartsdirect.com ..and i went to check the order status today and noticed that is said "special order" ...so i have NO idea... this place seems slow on shipping anyways i mean "orders usualy ship within 7-10 business days".....thats some good customer service!! then tack on the 13 bucks for shipping and handling for a small chip!!... ohh well the grand total was like 78 bucks

 

yes, their shipping and handling rates are killer but I have compared a few of their parts with shipping to the price from the local chevy dealer and they were still cheaper. Anyway, I dont know about the special order parts but when I have ordered stuff that wasnt special order they were usually here in less than a week.

Ben

 

well i hope its fast casue i got "real street drags" coming up and im supposed to have money races.......looks like im gonna have to no run.

 

Good luck. When is that supposed to be happening?

Ben

 

the 10th up at great lakes...someone thinks my car is a 16 second car and wants me to run one of them turbo 4 banger thunderbirds!! lol...they want the hit and i call the dollar amount. i mean this thing is a POS...completely stock with 170,000 miles and a huge system in the trunk. ran 16.8's last time i saw it. i can hand him his *** without that computer.

 

Actually I have one of those Mine is stock and I just have it because well its probably been 3 years now, but my parents forced me into it because my s-10 caught fire and they were tired of running me around. It is an 88. Stock they are decently fun to mess around with if you have a 5 speed but nothing near special. They can be fast when modified though. It depends on what year they are, but I know that my cousin has a fox body mustang with a pretty well built 351 windsor(cam, edlbrock intake/carb, ported heads, long tube headers w/ dual 3" exhaust, msd ignition and some other crap I am sure. He has 3.73 gears in it. He had his *** handed to him by a 87-88 turbo t-bird with the boost turned up and I am sure some other things too. Anyway, dont you think you can take him the way your car is or are you just trying to avoid damage to the motor? By the way I am in no way a ford guy, but I just have one that runs and gets good mileage for a daily driver. My T/A is my real car. What year is this guys car by the way.

Ben

 

This just gets better and better...
I finally got the computer and chip in and I put them in the car. Start the car, throws a code 51. So I look up code 51: faulty PROM or installation. I pulled it out and reseated it a few times, still got the code. I tried switching chips with my old computer, but that didn't work out at all. Anyone ever had this happen?

 

is that all the same stuff im getting?? (87 monte ss l69 computer and GM chip)..shoot i better not get that or ill be PISSSSSSSSED

 

I got ECM # 1228079 and chip # 24502456. They should work together, I guess one or the other is defective.

 

thats a diffearnt chip than what im getting....your is a 56..mine is a 57...whats the differance?

 

57 is for 82-85 LG4's without a knock sensor and 56 is for L69's and 85-87 LG4's with a knock sensor

 

ahh ok. thanks...well good luck with your problem! im still waiting for my chip.

 

GMPARTSDIRECT.COM just emailed me this morning, informing me that my order HAS been shipped and i should be recieving it on monday!!!!!!!!!!:lala: :lala: :lala: :lala: great start to my morning, and on top of that it was PAYDAY!!

 

when instaling the new computer, should you disconnect the battery? or is there certian stuff you have to disconnect before the computer?

 

I just got the same ecm, #I # 1228079 and chip # 24502456. I'll be installing it this Saturday in m car. I just replaced the LG4 in my 85 Camaro with a 350. I'll let you know how it goes.

As for changing the computer, I would assume you should disconnect the battery.

-Dave

 

so..how did it go?????? i got my l69 computer saturday, and my chip just came in like 5 min ago!!... but now i have to wait to put it in ..tonight im putting in my rebuilt carb and 1" carb spacer..then the bears packers game is on....dont know if ill have time to do the ecm or not....damn monday night football!!

 

The ecm and prom are easy to change. Shouldnt take long. Let us know when you get it done.

Ben

 

i know its not hard to change. but i dont have access to a timing light off hand, and i dont know what will happen if i leave my current timing (20* advanced) with the new computer. i dont wnat to put it in, start it, drive it, and get knock or ping...so i was gonna kick it down, then adjust it....but i will have it done for thursday for the drag stip!

 

Thats cool. Let us know how it goes.

Ben

 

Sorry for not replying sooner, been busy with homework, damn grad school!!

Anyway, the install went very very very easily. Took all of about 15 minutes and that was taking my time. Disconnected the battery, dropped the passenger side trim panel, and the the ecm. There are 2 harness connectors. The hardest part is removing the clip on bolts from the old ecm to put on the new one. I also tokk about 2 minutes and replaced the ESC unit with the one from the 350HO conversion.

I started it up, ran fine, no codes, but I found other problems I need to address. First my choke relay is stuck on. My choke needs adjusting. I need a stronger throttle return spring. And I need to dial in the IAB and the meetering jets. So, in about 2 weeks when I'm back home I'll get to work on it some more. But it does run better esp at idle. I didn't get a chance to drive it though.

Let us know how it works for you.

-Dave

 

to access the ECM, do you just need to take off that one panel on the bottom, or do you need to take the one that is directly infront of the passenger off as well?

 

Just the bottom one. From there you can get to the one or two screws holding the bracket in and it just drops down.

BTW Scoggin-Dickey is supposed to send me another chip, should come any day now.

 

got it all in, kicked timing down to 13ish and went for a drive...still had the same problem as before.. just not as bad...and on top of that a bog.... then i kicked timing up to 18 and it hesitated like a mother, then pulled HARD... im gonna play with my timingmore and see what happens...but so far no codes.

 

What rpm was the bog at? You also just put your rebuilt carb on right? Did you test drive it after the carb but before the computer?

Ben

 

havent put on the carb yet...damn spacer hasnt come yet!! damn ups!! well it better be my carb now, cause im out of options after that!...the bog was just a fluke,,, i wasnt thinking that i had it in a low gear(1st) then nailed it, and rpm's got to 4000ish and i got my hesitation, then shifted to 2nd and let off right away..thats where the bog was..totaly my fault. if the spacer isnt in tomorrow at 530, im putting the other carb on anyways without it, that computer seems to be good though. i bumped my timing up to 18, and after the hesitation at 4g's in first...ohh boy it PULLED.. my friend was like DAMN as the *** end of the car kicked out...very nice... now only to fix my initial problem......

 

Hey, Fattie92, i have 86' camaro, with the computer controlled q-jet carb. You said you did all the tuning to it like the AV flap i think it was. I want to know how to tune my carb up i hate the way my quadrabog is right now, is there much i can do? I just bought a rebuilt one from napa for $210. Its getting fine tuned for the mixture thing as we speak and all the normal stuff that has to be done to set it properly. Lemme know what you did to it and how much of an improvement there was

 

go here... TUNING FOR PERFORMANCE WITH YOUR CCQJET

i got better throtle response out of it.

 

I was just wondering the way it sounds all I have to do for my LG-4 83 T/A is get the L-69 chip and put it in the ECM and I will get more advance with my timing. If that is true I think I might have to get one of those. Is everything compatible I wonder?

 

you need a L69 computer as well. id get a 87 monte SS computer