74 Cj5 Build

I still had to route over/around the T-case.. I will try to get a photo of my routing

 

Couple of photos of the passenger side exhaust going over the T-case. Took some S-bends cut in half and re-welded to slightly different angles to make everything work, but it did.
Another thing to note for anyone doing a 70s or 80s 350 swap and then doing a TBI conversion, I think the thermostat in the earlier motors only called for 160°F. I swapped out to a 195°F last night. Also took a photo of the pass through speedometer coming off the Dana-20 Transfer case.
Another thing to note for those who might attempt a similar set up, the speedometer hook-up is 7/8" Dia. and works with most of the older GM mechanical speedometer cable parts. I had a hard time verifying for certain on the web.



Surprised me a bit when I pulled this 160° thermostat out... I didn't know they used to run that cool. I also didn't realized that the GMs don't use the O-ring gasket around the thermostat. Wasted a few minutes trying to hunt one of those down before the parts counter dude informed me that they don't use them. Neat.

I have also continued datalogging and trying to tune. I moved the O2 sensor about 8" down the pipe from the exhaust manifold. I think I may have been too close prior at about 2 inches. After a few goes at adding fuel, it's running better. Still not quite right though. It is constantly telling me I am too lean, but I can smell the richness at times, so I don't know if I believe the O2 sensor. Might try to buy a new O2 sensor tonight and see if the one I purchased is a dud.
For those of you interested, here is an image of my current Fuel map and graph.
I am also trying to figure out how to tune the spark advance table. This I know almost nothing about. I currently have the initial spark set at 0° on the crank. Been trying to read up on this, but my application is a touch different than most people out there. Most people are already playing with engines that had fuel injection to start with, my engine was a 1980 truck engine that was originally carbed. Many people on the other forums say to set the timing on the crank about 6° advance, not zero. It's been a couple of weeks since I was last messing with the base timing, but I feel like it idled like crap when I had advanced it past zero. Here is an image of my spark table. I might try to set it 6° advance again tonight and see if that makes any difference.

 

I'm curious. Have you changed .bin file from what you said you originally were using which was BCC code ASDW? Both the fuel and spark tables appear to be different.

 

Spark advance is mostly a function of RPM that climbs pretty quickly from idle to peak plateau around 2500-3000 rpm. Then as the load (MAP) goes up, it pulls 10-16 degrees of timing out to prevent pinging.

You also want a flat spot around your idle zone so the advance isn't moving around wildly while you're trying to control the idle speed.

Here's a typical curve I pulled from the web:

Notes:

• Flat spot in the idle area.
• Climbs pretty rapidly to 3000 RPM (in this case) and levels off at about 40 degrees advance
• Advance is reduced as the engine load goes up. This is like the vacuum advance on a distributor.

For your engine:

On the low load side of the graph, your idle timing should be 10-12 degrees an then it should climb up to 45+ degrees by 2500-3000rpm. On the high load side of the graph it should be around 36 degrees total advance above 3000rpm. You can make a smooth graph from there and it will get you pretty close. If you hear *any* pinging, pull timing out at that load/rpm.

 

Hey Ed, yes I switched the BIN to ASDW - The other tune didn't seem to run as well. The ASDW says it s for 87 R-V Truck 5.7L TBI 4 Spd Manual. This tune seems to be running okay, just not with the power or reliability I would expect. I think I am going to go ahead a try a new O2 sensor and see if my readings are any different.
I forgot I switched BINs, so i updated my post over at Gearhead: SBC 350 TBI Conversion Tuning Help
I also get the Error 51 on occasion. I need to research why I would be getting that, as this BIN should be perfectly compatible with the 7747.

 

Thanks for the explanation, Fireball. Do you know if my base timing should be set at 6° BTDC at the crank, or should it be left at 0°?
I will reduce my timing at idle. No load revving to 3000 RPM should see 45°+??
Hard to believe the stock tune for a TBI would be so far off from the 36° needed, maybe there is something behind the scenes that is increasing the spark advance? Isn't the table that I currently have currently showing about 10°+/- at under load at 3000 RPM? Seems way low!

Is this more what you would expect the table/graph to look like. I need to flatten out the idle range, but otherwise?

 

As far as your initial timing setting, you should check with a timing light. Adjust accordingly so the actuall timing matches what the computer thinks it is. That's the crux of it.

Agreed, your table seems way low. My experience is with a Megasquirt II and the tables are pretty clear for it. It's possible the GM software is doing other things to the spark advance I don't know about. Ideally you could find someone on a tuning forum with a similar engine to give you their tables as a baseline.

It would be interesting to rev it up with a timing light attached to see if the actual timing follows the table or if something else is also going on. You might need to add a timing tape to your damper pulley to get markings up in the 40 degree range.

I was lucky when I was tuning mine, two of my friends used to be engine calibration engineers at Chrysler and were a big help.

 

I appreciate the input. I will do some more research and digging. I added a little more information to my previous post before I realized you had replied. I was toying with the spark advance table. Might upload it to the ECM and start the Jeep, just to see what it does.

 

I ran my pass pipe in the frame rail,it just clears the case and rail.

 

Ryan, Leave your base timing at "0*" as that is what is set in your .bin. If you change the timing at the distributor and not in the program, the two will add across the entire spark advance table. Adjust your spark advance in the SA table.

No. Not possible so don't go there. Due to the design of the distributor and the program, the maximum advance possible is about 42* unless an offset is created in the program.

Your engine may be able to utilize 36* of advance but the manufactures tune the engines in a more mild manor.
With the GM ECM, numerous things effect timing other than just the base timing table. Items such as RPM, VE, EGR, engine temperature, PE (power enrichment), etc. effect engine timing. Look at your scalars and tables.

I suggest that you slow down a little bit. Concentrate on one item at a time. Get the engine starting consistently. Tune the idle and then work on the fuel table throughout the engine rpm range. Then work on the spark table. After that, you can go back and tweak an area that may need some minor adjustment. Working on multiple items simultaneously in a tune does nothing more than confuse the situation.

Last, I see no reason to buy another o2 sensor. Yours appears to be working correctly.

 

Thanks Ed, I have been going through all the different scalars and started noticing there are adders to the VE/spark table under different parameters/conditions, just like you say.

Engine starts every time. The whole map shows that I am running lean once I am warmed up. But man, it smells rich.
Hoping to get back out and do some more tuning this weekend.

 

Ryan, Just so I have a better understanding of your tuning equipment and process, could you answer a couple of questions? What equipment are you using to change your program? Are you removing your chip, burning a new program with say, a Burn2 and re-installing or are you using an emulator?
When looking at your latest log (4.28.2020 data log after work3 using 4.28.2020 Spark Advance Table and VE Table Increased.bin) I am having trouble trying to under why the BLM is reacting in the manner it is. It is almost reacting in the manor that I would expect the integrator to react. Maybe someone a lot smarter than me over at GearHead can explain and we will both learn.
When creating a log, try to be consistent when driving. I notice a lot of rapid throttle changes in your log. Even though traffic and road conditions dictate, try to hold a consistent speed. And it goes without saying, travel where you will have different speeds up hill and down. When you are completing your log, let the engine idle for a minute or two. This may require a few data logs before you make a program change.

 

The BLM's readings are very high, most likely because of vacuum leaks. The ecm is adding fuel because it's reading lean because of the vacuum leaks . check all hoses, and manifolds , before the O2 Sensor. BLM of 128 is perfect but not absolute. You should end up around there at idle of 700-800.

 

A misfire can lead to a lean reading while smelling rich. The non-firing cylinder passes the oxygen through without burning it, so the O2 sensor see excess oxygen and reads lean. The unburned fuel in the exhaust can make it smell rich.

 

Snoobly ,
I have a 1984 Buick Turbo V6 SFI in my '75 CJ5 .Here is an excellent ' Start Over ' from an old school Tuner pro. Use this and you'll be very Pleased. You #'s are all over the place . stop looking at timing , your crank & cam sensor will take care of that.

 

Also, I just read your T stat change out post. GM ECM's read closed loop at 160 degree's . No wonder your scan #'s are a mess . change it back & do the start over procedure. I did & now my CJ is the quickest Jeep on this forum..... Just Say'n.

 

Not to answer for snoobly but looking at the logs, the engine is idling at 750 rpm.

This is very true but again the engine logs do not indicate a misfire. You are correct of course as to the o2 sensor operation. The o2 sensor appears to be operating correctly. The way the gm ecm operates is, with the o2 signal received the fast responding fueling control called an integrator (INT) reacts to the fueling needs. The slow acting fuel control (BLM) follows the action of the integrator but again in a slow manor effectively smoothing out to fueling action. Something is preventing the BLM from following the actions of the INT but strangely, not all of the time.

I agree with, stop adjusting timing until fueling has been taken care of. BTW, this engine has neither crank nor cam sensor. It has a distributor.
It probably would not hurt to go back and re-scale the IAC as I see questionable action in the logs. The values given in the procedure you posted are lower than what the ecm calls for at idle. TPS voltage should be closer to 0.53 volts at idle.
With the original 160 degree thermostat, there were times the engine was not going into closed loop. With the new thermostat, the engine consistently is going into closed loop.

 

Hey Ed, I invested in an Ostrich 2.0 emulator for quicker tuning. I got tired of taking the chip in and out. Once I have the tune dialed in, I will burn the chip and install permanently.
Gearhead has been pretty quiet on my posts. I will post another when I do some more tuning and see if I can get someone smarter than me to take a look.
I do need to try be more consistent on my driving, I hear you there. There was a decent run in that log where I was going about 30 - 40 mph without hitting any traffic lights.

Hi Lockman, thanks for the input. I had a massive vacuum lead right at the beginning when I fired it up the first time. I fixed that one, but I will do a good search for any others. The Exhaust sounds and looks tight, I just rebuilt that. I think if there is one, it's on the intake side.

Hey Fireball, I don't hear a whole lot of backfire... Every now and then it does, but mainly when engine braking or if I do something weird with the heavy throttle.

I'm going to go back to the stock timing and leave it be for now. I tried to open the PDF, but it says that I do not have that privilege on this site.

I hear ya! But I have to agree with Ed on this one. It's been running a lot better with the 195° T-stat. I was also reading that 160 is a little on the chilly side for optimum wear on the internals of an engine. Granted the articles I was reading may be aimed a little more towards the more modern engine, 1990s and newer.

1. Very true, the engine is idling great most of the time right now.
2. Possibly could be a vacuum leak somewhere screwing with the INT & BLM not reflecting each other?
3. Going back to stock timing and I will leave it alone for the time being. By re-scale the IAC, you are referring to the "reset" where you jump the Diagnostic port and turn the key to the on position, unplug the IAC, etc...? Could also be that potential vacuum leak. Maybe I need to reset the TPS also, or maybe this one is on its way out. I'll be doing some investigating this weekend as time allows!

Thanks for all your input guys! It really helps me get thinking down different paths that I don't think about sometimes.

 

Earlier when you said, periodically you were see an error code 51, I wondered if you were using an emulator. Nothing wrong with the device just pay attention to the electrical connections. A loose connection could lead to the code.

Yes. With the engine idling, I would expect to see the IAC at about a 15-20 count and the TPS at .53 volts. I have noticed in the log the IAC at 0 when the engine was idling.

 

I am a carb guy for sure, but reading the above posts, I can really respect the knowledge you guys have regarding efi.