Fuel Management Question for 82 TRSC

[BADAZZV6]

I have a 87 GN and am relatively familiar with the "learning" of the fuel tables i.e. BLM and Integrator. Does my 82 TRSC try to adjust the lookup fuel tables for compensation as needed?? I think I understand the basics, just not sure about this electronic carb. How about something to read on the web.

Maynard

 

[b4black]

I don't think the CCC ECM's were that sophisticated. The ECM handles part throttle and idle. At WOT the primaries go full rich and the secondaries aren't ECM controlled. They use rod and hangers like a traditional quadrajet.

Nobody bothered to de-code the CCC language, so there isn't much out there. Most poeple (i.e. chevy guys) ditch the ECM, but then they can't up the boost.

 

[BADAZZV6]

Thanks Rich,
If I understand you correctly, this system will always use the same preset values from the lookup tables and continually correct for them if needed by changing the duty cycle of the mixture control solenoid, it won't rewrite the tables.
I really had no idea on what it was doing, that will help with tuning to resolve drivability issues.
I am waiting on a monitor 2000 I won from ebay, so I can start looking at things. WOT tuning is still the same, monitor knock, timing, boost and O2 (maybe EGT when I put it in), then tweak boost, timing and swap needles as necessary. I guess there's not much reason to monitor voltage as with the 87's.

I run a translator plus in my 87GN, sure would be nice to have that tunability in the 82.

I remember back in the day (1995) Snap On had a little book you could look up the PROM ID and see if it had been superceded due to corrections. Sound familiar? I would be curios to check mine.

 

[b4black]

There was a recall on an early '82 PROM. It had something to do with WOT TCC lock up.

The OTC is great and I use it from time to time, but I prefer the real time output of the Casper's knock gauge (which I still haven't got around to installing in my '82). I found with my '83 that it knocks all the time under stock conidtions. With 9 psi boost, 93 octane and a 165° t-stat, I need to pulling timing to keep the knock down (I pull ½° per psi with my MSD BTM).

Many Carb/Turbo guys aren't even willing to hook up a boost gauge, so convining them to run a knock gauge is difficult. It will be good to see what your SFI experiance brings to tuning a Carb/Turbo.

 

[BADAZZV6]

Well I took tired iron for its maiden voyage down the street last night. Probably should register it before I get too brave. I still need to finish the exhaust and some small issues, but here's what I noticed. I had spark knock at every level. Retimed it to 15 BTDC in gear vs neutral from before, idle is still a little high at 1000rpms, it was struggling to idle at 600rpms. Vacuum is at 11 inches @1000rpms, but that might be due to the higher then spec idle.
On the second trip spark knock was much better and only on heavy acceleration. Once I was able to get it going I got into it trying to open the 4 barrels and build boost, but neither happened.
I could hear a little spark knock and didn't want to push it. I think I need to back the timing down for the interm as I have a gallon or two of 2 year old 87 octane gas mixed with 6 gallons of fresh 93. I installed a 160 T-stat, gutted cat, no smog pump/pipes and 9" K&N on the bonnet. The carb has not been run in several years which I suspect is my idling problem, but it is getting better all the time. I still need to install an inline fuel filter and replace the heater under the carb with a gasket. I need to check the 4 barrels to ensure they do in fact work and the choke ins't locking them out. I also might unhook the EGR, but I don't think it will make a difference with the spark knock or will it?? It doesn't hesitate on acceleration. I'm going to mod the air intake to get it down in cooler air. It has been a lot of work to this point, but now it is just housekeeping on small issues and drivability training.

 

[b4black]

When you set the timing, are you unhooking to the 4-pin connector?

Poor idle is likely a vacuum leak or the IAC in the carb. (I've never messed with IAC myself). You might want to get a book called Rochester Carburetors by Doug Roe. Most big bookstores have it.

Unhooking the EGR will cuase knock at highway cruise. Heavy acceleration, it shuts off. Try T'ing in a vacuum gauge between the solenoid and the EGR. It will help you see when the ECM is turning it on and off.

If you can here the knock, maybe the ESC isn't working. You'll know once you get the scan tool on it.


Good to see your at least running down the road.

 

[BADAZZV6]

I did unhook the 4 pin connector.

Good idea on the vac gauge tapped into the EGR. I'll check for vacuum leaks also. Some vac lines were missing, some were rotted etc and I had replaced them all. Your making me wonder if I have the EGR valve plugged into the correct place. I'll check it against the vacuum diagram.

I got the scan tool now, so I'm gonna check the ESC along with everything else. I have never used the OTC 2000, so I gotta read on that as well. I also picked up a factory shop manual, so I'll give that a read to.

Thanks for the tips

 

[BADAZZV6]

I checked the plumbing of the EGR and it is correct per the vacuum diagram. One thing I did notice, I tapped into the EGR hose to run my boost gauge thinking it was base vacuum. Is this wrong? Is there pressure at the EGR valve during boost? If there is no boost pressure at the EGR, maybe that explains the no boost condition the other night, even though I could hear the turbo I had zero on the gauge. When I removed the smog pump I also capped off the EGR purge solenoid. Is that incorrect? Should I let it bleed to atmosphere?

I currently don't have time to fiddle with it, maybe in a few days.

 

[b4black]

The EGR is connected to vacuum at the carb, which never sees boost. There is a "boost circuit" that you need to tap into.

In this image, the boost circuit is the turbo's compressor housing - map sensor - wastegate actuator. Not pictured is a line going to the pressure switch for the dash lights. T into this circuit (using the pressure switch tube is the easiest).

The other vacuum line on the actuator to the plenum is uncessary. It serves no function and the vacuum side of the actuator tends to leak, so remove this line and cap off the plenum port.


The smog pump and EGR have nothing to do with each other. I'd open the vent back up. It might be holding the EGR open.

 

[BADAZZV6]

I will get that done and report back. Just a thought here, if I tap into the compressor for the boost gauge, will I be able to read vacuum accurately? Not that it matters, cause I could always pop on a vac gauge somewhere else if I needed to. Just wondering if the gauge will be dual purpose (boost & Vac) or single.

 

[b4black]

Tapping into compressor is the same as tapping into the intake manifold. You'll see vacuum and pressure.

 

[BADAZZV6]

I have rerouted the vac line for the boost gauge. I am now getting 9psi boost. This turbo is much quieter than the 87 with a K&N under the hood. I can just about hear it.

I also plugged off the vac side of the actuator.

I disconnected the EGR valve and plugged off the line, idle went up several hundred RPM's. I re-verified base timing was still at 15 BTDC and reset the idle to 600RPM's in drive. Vacuum has increased from 11 to around 16 and steady. It is idling really nice. On the test drive I still had knock, but it has been significantly reduced and only on heavier acceleration, probably due to disconnecting the EGR.

I attempted to hook the EGR back up and as soon as I connected it I could see the diaphram moving toward the firewall and the idle dropped. I pulled it off before it stalled and plugged it off. It appears to be plumbed correctly per the vac diagrams (your 83 & my 82). My experience tells me that the EGR should not see base vacuum at idle. It has to be plumbed wrong or the circuit is faulty, I think I need to start looking at that. I haven't been able to find a description of how the circuit works in the shop manual.
Is there anything in the carb that could be faulty and allowing base vacuum??
I have since backed timing off to 10 BTDC which has helped, but has not eliminated knock. I'll bump it up later as it gets better.

I checked and could not find any vacuum leaks, then I cupped my hands over the carb and the idle went up a little. I'll have to keep looking for that one. I'll be pullling the carb soon, so I'll tighten all the screws on top and under the base and replace the ceramic heater with a gasket. Maybe that will help.

Have you got any thoughts on the EGR circuit??

 

[b4black]

The EGR should be routed thru either the red or white solenoid bolted to the back of the carb. (I think whichever is on top, IIRC). The EGR should be closed at idle and WOT. It really only needs to be open when you are crusing along at a constant speed or lightly accelerating.

Since the EGR's open at idle, I'd suspect the solenoid is hung open. Try hooking up a volt meter or test light to the solenoid leads to confirm the ECM is trying to turn it on and off. I'm not sure if the solenoid is normally open or closed (my guess is closed).

9 psi is the factory setting and indicates that things are working. If your secondaries where hanging up, you would only get ~6 psi. 16" of vacuum sounds good. My '83 gets 15".

You're making good progress.