1991 Eliminator Resto-Mod

[ghetdjc320]

All finished and back on the road. Handling is the best I’ve ever felt in a truck. 

[howeitsdone]

Where are the finished photos??

[fiatslug87]

[MiNi Beast]

[howeitsdone]

Why are you torturing us? 

[ghetdjc320]

Here are some pics…

 

Working on the stand alone ecu. Settled on MaxxECU Sport. I desoldered a harness connector from and old ecu I had laying around. I’m now adding pigtails to each terminal. The idea is to have my MaxxECU plug into the stock harness. I recently replaced my 60 pin harness connector as well with a new one from Mopar. At the moment I plan on just getting a plug and play setup working. I will eventually switch to a wasted spark system and delete the existing coil and distributor. The ecu is compatible with all stock cam and crank triggers and will even control the alternator field requires on obd1 setups. More info coming in the next few weeks.

[ghetdjc320]

Potting curing

[boxyjeep]

That's epic.  Interested to see how it ends up.

[ghetdjc320]

Potting fully cured. Ecu on the way. I’ll be using some unused cavities on the 60 pin connector and adding the ignition outputs to the harness for the extra 2 coils (3 total coils driving 2 cyl each). If anyone has a simplified description about what the heck the difference is between the “ac request” and “ac select” inputs on the stock ecu are that would be perfect. I’ve studied the wiring harness diagrams and I don’t see what the difference is between the two. For now, I’m just going to setup the “ac request” input and wire in the “ac clutch activation” output. This ecu also has full alternator control which is a plus. Only thing I need to add now is a coil igniter/amplifier.

[ghetdjc320]

On 11/2/2021 at 1:47 PM, ghetdjc320 said:

If anyone has a simplified description about what the heck the difference is between the “ac request” and “ac select” inputs on the stock ecu are that would be perfect. I’ve studied the wiring harness diagrams and I don’t see what the difference is between the two. For now, I’m just going to setup the “ac request” input and wire in the “ac clutch activation” output.

Wondering if @Minuit has any insights on this circuit. Just getting the inputs and outputs mapped and setup in the software

[Red Mistress]

On 10/12/2021 at 5:32 AM, ghetdjc320 said:

 I had a new Iron Man Fab track bar system which has a double shear mount, adjustable bar with enduro joint and a frame cross brace to tie in the passenger frame rail. This is a massive improvement over the stock system. 
Also had the metal cloak dual rate springs and the Iron Man Fab steering system brace which ads a great deal of support to the steering system by bracing the steering box both above and below the pitman arm. It ties in both frame rails also and uses a pillow bearing for a super solid fit. My steering box is a stock unit that was rebuilt by PSC. It’s a very nice box and now with this setup it’s like rack and pinion steering, seriously, it’s super slick. Also nice change of pace to bolt on some mods vs all the restoration work. 

 

 

Nice new powder coated steel mod parts! 

Like to see more pics of this track bar / steering setup.

 

I'm wondering if can still use the OEM front skid plate?

 

Looks like you also raised & gusseted the sway bar mount.

 

Truck looking good !

 

 

 

[Minuit]

4 hours ago, ghetdjc320 said:

Wondering if @Minuit has any insights on this circuit. Just getting the inputs and outputs mapped and setup in the software

I'll take a look at the FSM and fuel injection manuals when I get home. I think I know but need to verify.

 

[ghetdjc320]

7 hours ago, Red Mistress said:

Like to see more pics of this track bar / steering setup.

 

I'm wondering if can still use the OEM front skid plate?

 

Looks like you also raised & gusseted the sway bar mount.

 

Truck looking good !

 

 

 

Ill take some pictures of that setup from different angles for you. 

[ghetdjc320]

On 11/3/2021 at 11:44 PM, Red Mistress said:

Like to see more pics of this track bar / steering setup.

 

I'm wondering if can still use the OEM front skid plate?

 

Looks like you also raised & gusseted the sway bar mount.

 

Truck looking good !

 

 

 

here are some of those pics:

 

 

[ghetdjc320]

And here are some pics of the truck for kicks. You’ll notice there is no more body seam between the cab corners and cab back.

[ghetdjc320]

On another note, the ecu and all wiring and adapters are in. Not sure exactly when I’m going to be installing it just yet but hopefully soon. Having a slight overfueling issue when trying to restart once the truck has been sitting a few minutes after driving. I suspect the fuel map for cts is off for the injectors I’m running. I have to start the truck and immediately open the throttle to clear out the fuel. 

[ghetdjc320]

Well it’s time to just go for it and build the ecu harness. I tested the ecu today as I wanted to be sure it would recognize the stock 4.0 HO cam/crank triggers. How these triggers functioned was always a bit odd to me as I’m used to seeing a missing tooth flywheel that would always indicate #1 cylinder is at TDC. The cam sensor would then tell you if it was on the compression or exhaust stroke. The HO flywheel is nothing like that. It has 3 sets of 4 holes in Y pattern on the flywheel/flex plate. Here is what that looks like:

 

The cam turns only 1 Revolution for every 2 revolutions (720*) of crankshaft rotation. Because of this, the cam sensor can help you determine when the engine is at TDC on the compression stroke. Here is what the HO cam sensor looks like on a 94-99 distributor:

 

It’s worth noting that all the HO years ultimately give the same signal. Even the later model distributorless systems introduced in 99 had a cam sensor that fits in that same distributor hole to give the ecu TDC timing. This new ecu can handle sequential 6 cyl spark using either coil on plug or a wasted spark system using that later model sensor. You could just leave the old distributor in also but I like the cleaner look of the 99-03 cam sensors. 04-06 had a bit different looking and somewhat failure prone cam sensor/opda unit. 
 

So I wanted to make sure the ecu would read these stock sensors before I moved forward. It does! Here is the oscilloscope it was reading from the cam and crank triggers:

 

the top readings in orange are the crank trigger and they correspond to the holes on the tone ring on the flywheel/flex plate. Every 2 “spikes” represent 1 cylinder. The lower blue line is the cam sensor. You’ll see that it goes low for 12 crank triggers and then goes high for 12 crank triggers. Every 2 crank triggers is a cylinder event. It’s pretty simple when you think about it. 1,5 3,6 2,4. The cam triggers high on compression stroke and triggers low  on the exhaust stroke. Thus you can find TDC on either stroke at any given engine RPM. 
 

Note also that the original supply voltage for these sensors is 8v from the ecu bu I am supplying them with 5v from the new ecu and the readings are just fine. 

 

 

[ghetdjc320]

One caveat I had not anticipated was that this particular ecu mode cannot natively control the GM style IAC valve in the throttle body. Even the stock ecu never did a great job of that. So I removed the throttle body set screw and flipped it over for easy access from above. Set my idle to a nice 850-900 without load. Since our temps are always the same I don’t need any extra idle anyways. Actually works remarkably well even on the stock injection! So if you iac is acting up try this. I’ve done this with motor sports vehicle before as well with great results. 

[Ωhm]

17 hours ago, ghetdjc320 said:

Every 2 “spikes” represent 1 cylinder.

 

17 hours ago, ghetdjc320 said:

Every 2 crank triggers is a cylinder event.

 

Don't 4 "spikes" make up one (1) cylinder event? I'm a RENIX guy asking.

[ghetdjc320]

50 minutes ago, Ωhm said:

 

 

Don't 4 "spikes" make up one (1) cylinder event? I'm a RENIX guy asking.

Since the crank is spinning twice as fast as the cam and the cam sensor is “open” half the time and “closed” the other half of a single revolution, then crank 2 triggers would equal one cylinder. Since cylinders 1 and 5 go off in close sequence, it would seem like the oscilloscope is registering each 2 triggers as a cylinder. The 3 groups of 4 triggers would represent the sequential pairing of cylinders 1-5, 3-6, and 2-4. At least, that’s what I’m basing my trigger info on lol. Ultimately the crank pattern for the 4.0 HO is

18-2-2-2

[Ωhm]

In your scope shot it looks like 3 cylinders (12 "spikes") are on the cam signal LOW. Too me it looks like it could be either cylinders 153 or 624. Like you said 2 cranks=1 cam, so half a cam is only 3 cylinders.

[ghetdjc320]

48 minutes ago, Ωhm said:

In your scope shot it looks like 3 cylinders (12 "spikes") are on the cam signal LOW. Too me it looks like it could be either cylinders 153 or 624. Like you said 2 cranks=1 cam, so half a cam is only 3 cylinders.

Half a cam is 6 cyl at TDC just either on the exhaust or comp stroke. 

[Ωhm]

Both cyl#1 and cyl#6 are at TDC at the same time. Cam signal, if its HI or LOW, will determine which one of these two cylinders need the injector (fuel). Same applies for cyl#5/cyl#2 or cyl#3/cyl#4.

[ghetdjc320]

1 hour ago, Ωhm said:

Both cyl#1 and cyl#6 are at TDC at the same time. Cam signal, if its HI or LOW, will determine which one of these two cylinders need the injector (fuel). Same applies for cyl#5/cyl#2 or cyl#3/cyl#4.

Yes that’s true. But I believe the cam is only syncing cylinder 1 to start the sequential injection sequence. What I’m not sure about yet (will have to pull the cap to know for sure) is whether the falling or rising signal is the compression stroke. But that makes sense if each set of triggers represents one cylinder. The computer could never know which cylinder it’s on without the cam sensor but the order of the plug wires makes the firing order sequential. Thus one could control timing off of just a crank sensor. I’m curious as to why there need to be 4 marks per cylinder though.  All well, I’m just glad the trigger pattern is supported in the ecu. 

[ghetdjc320]

Took a bit of a detour and worked on the hood. The body shop that did the original body work did a terrible job so I’m redoing it all. I wanted the hood scoop to be better profiled into the hood. Also wanted to eliminate the small area behind the scoop on the hood where factory bead rolled design was. Here are some pics. Look closely and you’ll see the differences. Also had rust to eliminate as wel as filling some old bolt holes. I used a resin based filler to adhere the scoop this time and had much better results. Have just a few more spots to touch up before a final 400 grit sanding and base coat. Will also finally be installing the hood light thanks to @eaglescout526 along with restregón the latches and replacing the pushrod guides.