1994 454 TBI runs rough, misfires, backfires, dark exhaust

[M & J]

You don't need a scan tool for something as simple as OBD1. I used a program called WINALDL  when setting up the supercharger on my wife's 92 Blazer running OBD1. Keep it simple.
I do agree with others though Pete. I'd get the petrol side sorted before mucking with the Lp side

[Froggy1936]

Sleeth    Cheap ??  i??There are two complete for sale $400.00 That will buy a lot of darts ! 

[Froggy1936]

MJ More info about WINALDL  is this a computer program ?  Is there a cable needed ? Frank  As I was only involved with VW,s from 1972 to 2000 I have never diagnosed any American vehicles   Frank

[M & J]

VW man eh Frank? Good to know.

It's been years but yes, I had to build a serial cable to interface with the ALDL connector. There was a circuit that had to be built and added to interface to a laptop serial port.
It's been so long Frank, I don't know if WINALDL  is still around or not. Dave uses one also that might be more up to date.

[SLEETH]

that is  cheap considering what  might be spent  on parts /pieces and time spent mI sold one  last  year for 250 Canadian=cheap .sorry frank where I come from time is money(but that's  just my opinion)

[DaveVA78Chieftain]

One of the best OBD1 program monitors: TunerPro

I have used it a lot on my 92 Lumina APV with a 3.8L MPI ODB1.  Even adapted it to read the ABS system on my Lumina APV.
Takes some research to establish what definition files you need.

[M & J]

http://winaldl.joby.se 

There's the link for WINALDL Frank and Pete. Dave's Tuner pro is more up to date but at least you can view both and experiment.
Cheers.

[bluebird]

What controls the lp part of this system? Is the same ecm used? If so that may be part of the problem. If the memcal has been reprogrammed, it may have a bad file programmed in it.  If the TBI unit is working like it should you shouldn't be rich in open loop.

[Froggy1936]

One of the best OBD1 program monitors: TunerPro

I have used it a lot on my 92 Lumina APV with a 3.8L MPI ODB1.  Even adapted it to read the ABS system on my Lumina APV.
Takes some research to establish what definition files you need.

Dave what is the procedure  for connecting computer to ALDL  My main concern is diagnosing  4L80E problems I am not sure if tunerpro does transmissions Frank

[kennyrodgers]

Hi Guys,
I've ordered the next one up from this. It will allow me to do the same as the video with an android device and also connect via bluetooth to my laptop where I can use Tuner pro or similar for real time scanning.
Roughly $100 shipped to the UK. 
https://www.youtube.com/watch?v=fibnQ7axKB4


Bluebird,
The propane system has it's own ECU. When propane is selected it shuts power off to the injectors and the propane AFR mixture is controlled by a step motor via info supplied from the stock o2 sensor. There's also some sort of emulator for the petrol injectors so the vehicle ecu doesn't go into meltdown.

[bluebird]

OK then. One other thing comes to mind, when you installed the larger injectors, the ecm is set up for stock injectors and the ecm won't change the pulse width until it goes into closed loop. If the injectors are spraying correctly and it still rich, then you may have to get someone that can actually see the program. A regular scan tool doesn't show the fuel program in the ecm, nor can you change it. I would be looking for a stock throttle body. Putting in larger injectors is OK for a modified engine where there is a programming change, but on a stock engine I don't know if you will ever get it right. I used to burn my own chips for a 87 GTA back 18 years ago, and it takes a lot of time getting them to run right when you start modifying them. What did this have in it for injectors stock? If it had 50 lb per hour and you went to 80 lb per hour I doubt you will get it with out a reprogramming of the ecm. Try turning down the fuel pressure if you have an adjustable regulator and see if that helps.

[SLEETH]

he may  have a defective(internal )fuel regulator . you can see a lot with a scanner ie: the block learn & the integrator readings(which adjust the fuel trim)ie: injector pulse width ect ect

[kennyrodgers]

Hey Guys,
These are the injectors I bought, I'm pretty confident they're the correct ones for my application. I spoke to the seller on the phone and he also said they were the right ones for my year and engine. I know the 94 ran a higher pump pressure than previous years but other than they should be the right ones.
http://www.ebay.co.uk/itm/111132764823?_trksid=p2055119.m1438.l2649&ssPageName=STRK%3AMEBIDX%3AIT


Whilst we were in there we also rebuilt the throttle body with a full kit, gaskets, diaphragm etc etc, the only thing we didn't change was the spring as I read that's not recommended due to the higher pump pressure.
Thanks again for the input chaps, it's very much appreciated.

[bluebird]

What is your fuel pressure? I have found they have two different 80# injectors. Some were rated at 9/13# and some were rated at 28/32# pressure. If you have the 9/13 # injectors and have 28/32 lbs of fuel pressure then you are spraying way more fuel than needed.

[kennyrodgers]

Hi Bluebird,
I've not tested it to be honest but I'm presuming it's 28/32 as per 94. I had no idea there were two different injectors.
I'll have a look at my old ones today and see if they give up any clues.
Thanks for the pointer on that.

[kennyrodgers]

Right then,
My old injectors have a pink top and from what I can gather that is part no 17104288.
When I've looked at other suppliers they say it's equivalent to 17113080 / 17113081 which is what I've got.


I'm not quite so confident any more though lol.
W% 
I have a quadrajet of an Olds 350 sat doing nothing. I'm half tempted to throw that on at this stage........but i'll keep at it.

I'm going to take my old injectors to a local fuel injection specialist and get them rebuilt, throw 'em back in and see what happens.
In other news.... I moved the rig to her new home today. She threw the 45 code again after I presume she went into closed loop as she stuttered at idle when the CEL light came on. Switched her off for a while then she threw it again when I got to the new place approx 5 miles away whilst idling in the yard.
She did however shift into 3rd on one occasion.
Also, new electromagnetic switch fitted on the propane tank and still nothing.
Oh the joy !

[DaveVA78Chieftain]

GM Fuel pump assembly P/N for 1994 is 25163472 which uses a AC Delco EP377 fuel pump.
Note:  You have to add the part to the cart and view the item in the cart info to see the full GM P/N.

The AC Delco EP377 fuel pump is rated at 30psi. TBI Fuel Pumps Specifications and Regulator Springs!


Looks like the current GM injector number is 17113080 or 19110534.

Are you sure this is a 94 chassis and not a 94 Winnebago mounted on a 93 chassis?  Might change things:
http://www.gmpartseast.com/Page_Product/PartList.aspx?MakeUrl=chevy&CatalogUrl=1993-p30&ComponentCode=TX0300203&SectionCode=03&EngineCode=L19&TransmissionCode=M40&ModelCode=&Vin=&ProductionDate=&VehicleInfo=&CatalogCode=53P&Year=

[M & J]

Oh. Good call Dave on the chassis.

[kennyrodgers]

Cheers Guys,
According to my vin it's a 94 chassis, the pink/purple injector equates to 94 as well.
I found this.......
http://www.gearhead-efi.com/Fuel-Injection/showthread.php?81-GM-TBI-Injector-size-color-and-part-numbers

[BrianB]

Are you sure this is a 94 chassis and not a 94 Winnebago mounted on a 93 chassis?

Looking at / decoding the VIN will tell you what year the chassis was built.

[kennyrodgers]

Got the propane working today guys.
The live that runs the length of the coach to the tank valve solenoid had a break in it right above where the folded steps are.
We'd have found it sooner had we started back to front  but of course we started at the front.  As a result though we've changed out a lot of the wiring which for a certified system was nothing short of shocking.
She seems quite happy on it.
Progress.....now to sort that 45 Code lol.

[bluebird]

With the rich condition code, have you tried to reduce the fuel pressure?. The ecm should be cutting fuel to keep from getting the 45.  You will ruin the 02 sensor in short order if you don't get it. If it runs good on LP, how does it drive? Does it shift like it's supposed to?

[SLEETH]

if he could access the live data stream = he could see what the  block learn & the integrator is doing  to adjust the fuel trim! as I stated earlier= throwing darts will waste time & money

[kennyrodgers]

Hi Sleeth,
Just waiting for the scanner to arrive in the UK. Once i can figure that stuff out I'll post it up as soon as.
Cheers Buddy.

[SLEETH]

best route to go=that way you can view what all the inputs are reading/and then view what the ecm outputs are being commanded!(what goes in must come out)
who knows u might  have a bad quad driver in the ecm