93 3500 Regular Cab - 502/Accel-Ram Swap

[amsterdam96]

It would be quite a bit of work, just a heads up, but the easiest route would probably be to get a harness and computer out of a vehicle with the 0411, since youd need to switch it to OBD2. One other thing I'm not sure about is if there is a crank position sensor in your engine. If not one would need to be added for a newer computer, which isn't easy. The next issue is the price of tuning software, for example hp tuners is about $400 ( I think?) Plus credits.
I would definitely call this a back up plan. If you can get the truck running on the old computer, I'd probably stick with it.

Thanks for the insight, I'll keep it in mind as a back-up like you've said. About the crank position sensor, I'm not entirely sure. If i find a technical drawing of a 502 with all the sensor positions, I'll have a look.

 

[amsterdam96]

I think the confusion here is batch fire vs sequential. Batch fire will activate each bank of injectors twice per crankshaft revolution. Back in the day GM hadn’t figured out sequential port injection. That is where each individual injector fires at the corresponding time.

All the early EFI was like this until the LT1 came out. Performance wise, there isn’t much to be gained. I’m guessing GM never bothered with sequential port injection until the government squeezed them for better emissions.

If you didn’t have the 4L80E, the go to ECM is the ‘730. These were found in early 90s port injected vehicles. F bodies, FWD cars, ect.

The next step would be GMs first PCM, and the preferred one here is the ‘427. This has been pretty well hacked.

While a much better PCM, I think the ‘411 would be my last choice for this setup. It’s going to require some parts that I’m not sure exist. The MkVI BBC has the required timing set with 4x crank wheel and cover with the crankshaft position sensor. I don’t know enough about BBCs to know if these parts can be swapped over.

For my money, I’d use the equipment you have. Use TunerPro to find out if you can any faulty sensors. It seems like you are still guessing about your fuel pressure. Invest in a test kit. If you plan to stay EFI, you will always need it. It sounds like you have verified with a noid light that the injectors should be pulsing. Depending on how long this has sat for, maybe the injectors are gummed up. They may need to be removed and an ultrasonic cleaning. Worst case, a new set of injectors won’t set you back too far.

This truck is simple. You can get it running. Don’t give up on it.

Thanks for all that information! We just made sure all the mechanical injection & fuel/air related stuff is in order. Which it appears to be the injectors are also fine on 1 & 3 along with plugs, injector plugs and spark, but when swapped over to 2 & 4, it won't run. We found a small pressurised fuel cell in the line & we realise this providing excess fuel (set up from when this truck was used for 1/4 mile runs or something of that nature). We're going to run a fuel-pressure test (I will buy one if I need it repeatedly like you've said) and then we're going to revert it to one fuel pump/low pressure fuel delivery and see if it's running on more than 2 cyls.

I'm gonna see if I can get a data-log/error codes with TunerPro and a serial 9 adapter. I've read somewhere that I need to run a certain file to get TunerPro to pull a log, does anyone know what kind of file that'd be? Can I write this command manually? Are these files readily available somewhere?

 

[amsterdam96]

After rereading it definitely sounds like the injectors may needed to be cleaned or rebuilt. Until you are certain that you have at least 40psi of fuel pressure under load, we are all just guessing.

Post some pics of the missing or disconnected sensors and damaged wiring. We can help get it back together.

There are two disconnected temperature sensors just under the valve cover on either side, the connections are very flimsy but they're there and they can be held on. Shouldn't be hard to fix. I can post some photos if any finds this a weird position for temp sensors.

 

[Amsterdamned96]

Sorry to revive an older thread, but I'm OP, I've lost access to the older account & unable to recover the details. I've made another thread in which I'll be posting questions & photos as I go along. I've learned a lot about this car in the meantime but there's a lot more to learn still. Any help would be greatly appreciated.

 

[Amsterdamned96]

The emulator replaces the old PROM chips that you would burn. I used one on my old 350 TPI. It was amazing to make real time changes to the tune. The Moates adapter goes between the CALPAC I think it’s called and the emulator.

I would try to email or call Moates. All this stuff is for OEM GM ECMs. I have zero knowledge of that Accel equipment, or if Moates hardware will work with it.

If you are going to get serious with the tuning there are better ECM/PCMs out there. I’m sure that Accel ECM is one of the old slower types. The data stream would only update every 10sec or something. The later model OBD ECMs were would provide data samples at several times per second. This provides much more data to tune with.

Good luck.

Sorry for replying to an old post of yours. I've acquired TunerPro & MAP calibration software. There turned out to be so much damaged wiring that I've decided to pull the engine an re-do the wiring harness. I also noticed 7.4 stamped on the block, So I was eager to measure the bore. So now I'm re-doing the gaskets & bearings as well.
Like I said, I'm currently trying to fix the wiring, so I'm looking to get the right terminals and connectors together before Christmas so that I can re-pin and swap out all damaged wiring and mount the harness properly so it doesn't get burnt again. Once it's all back together I plan on contacting say Moates or someone familiar with EFI and look into reprogramming or replacing this ECU at an affordable rate. I've even considered Holley but I'm hoping there's an alternative that doesn't cost 1200$.

 

[Amsterdamned96]

I'm still in the same boat, I'm re-sealing the engine in the coming month. I had a bent connecting rod, the bore measures stock 454. It's got the peanut port heads. Does have headers and the Accel mpfi intake. I bought 8 new Bosch EV 6 injectors, the closest to the original 36lb/hr ones that came with this top-end kit. The cam is basically an RV cam with increased lift but stock LSA. I'm still trying to work out how to re-use the original DFI system from Accel that's obsolete, apparently the distributor was set along with the installation of the unit and it was syncronized as such, as there is no cam/crank-position sensor. If I'm not mistaken there is no throttle position sensor either but since it's been so long since I took apart the throttle body I can't say for certain. If I can't fix it, I do still have a speeduino and could go wasted-spark/batch fire instead of having to swap to a newer ignition system and Megasquirt III.

I'm doing a complete frame-off, plan on using an engine hoist to take off the ext. cab, with the doors as well as interior fully stripped. I'm going to undercoat the frame with a 2 component epoxy used for boats after sandblasting. I've contemplated to do the seals on the transmission as it's always had a red droplet on the drain plug and this would be the perfect time. Does anyone on the forum have experience with either older ECUs pre-dating OBD standards? Or with 4L80es?

If anyone else would like to chime in as to what I could do with this 7.4L to make sure that it'll run right?

Once the con-rod has arrived and the weather is good enough to paint outdoors I'll be throwing it all back together as quick as possible, leaving me lots of time to ensure I've ordered all necessary parts and done the right prep-work. Maybe I'll paint the body if I can get access to a spray booth considering everything is coming apart but I'd rather concentrate my efforts on the mechanical aspects until it's passed technical inspection. I have yet to rewire the truck but I think this is best done towards the end when I can ensure that traces/cables are the right length, for now I'm hoarding GM-style terminals and connector.

 

[HotWheelsBurban]

I'm still in the same boat, I'm re-sealing the engine in the coming month. I had a bent connecting rod, the bore measures stock 454. It's got the peanut port heads. Does have headers and the Accel mpfi intake. I bought 8 new Bosch EV 6 injectors, the closest to the original 36lb/hr ones that came with this top-end kit. The cam is basically an RV cam with increased lift but stock LSA. I'm still trying to work out how to re-use the original DFI system from Accel that's obsolete, apparently the distributor was set along with the installation of the unit and it was syncronized as such, as there is no cam/crank-position sensor. If I'm not mistaken there is no throttle position sensor either but since it's been so long since I took apart the throttle body I can't say for certain. If I can't fix it, I do still have a speeduino and could go wasted-spark/batch fire instead of having to swap to a newer ignition system and Megasquirt III.

I'm doing a complete frame-off, plan on using an engine hoist to take off the ext. cab, with the doors as well as interior fully stripped. I'm going to undercoat the frame with a 2 component epoxy used for boats after sandblasting. I've contemplated to do the seals on the transmission as it's always had a red droplet on the drain plug and this would be the perfect time. Does anyone on the forum have experience with either older ECUs pre-dating OBD standards? Or with 4L80es?

If anyone else would like to chime in as to what I could do with this 7.4L to make sure that it'll run right?

Once the con-rod has arrived and the weather is good enough to paint outdoors I'll be throwing it all back together as quick as possible, leaving me lots of time to ensure I've ordered all necessary parts and done the right prep-work. Maybe I'll paint the body if I can get access to a spray booth considering everything is coming apart but I'd rather concentrate my efforts on the mechanical aspects until it's passed technical inspection. I have yet to rewire the truck but I think this is best done towards the end when I can ensure that traces/cables are the right length, for now I'm hoarding GM-style terminals and connector.

Good to hear you're making progress on it. How is parts availability in Spain? I guess the online companies are your best bet....

 

[Amsterdamned96]

Good to hear you're making progress on it. How is parts availability in Spain? I guess the online companies are your best bet....

Yeah, I ordered the TBI sensors and bare-minimum to get the engine in order. I shelled out just shy off of a grand and everything I've bought could fit in a shoebox. OEM Door hinge pings, freeze plugs, cam bearings, oil galley plugs, a NOS or reman'ed con-rod, in-tank AC delco pump, gasket set for rec intake ports both top & bottom-end and a gasket sheet for the Accel Ram intake plenum. Everything OEM and NOS IAC and TPS but it's still appalling. a 1/3 went to shipping & duties, the other third to the two gasket sets for all machined surfaces on the block and the remaining three-hundred on the misc. bits. I forgot to mention some Metri-pack terminals to rewire, a pack of 50.
Seems pretty aweful to me as most of the parts are readily available overseas and at a mere fraction of the price.
Thanks for asking though.