Fun with troubleshooting leanness (and 5th gear cruising temps) Options

[emerygt350]

So I have been playing with adding resistance to the cht to bump my mixture. Messing with the mps was not getting me to where I wanted to be I wanted something a little more global. Anyway, bought a 10 dollar Bluetooth relay. Set it up so one channel was clean the other had 50ohms resistance in it. As I am driving I can switch back and forth and watch the results on the cht and AFR. 50 is really working well (this is all in addition to my 250ohm found on 73s). Now I have added another 20 ohms to the alternate so the relay will switch between 50 and 70. It ain't pretty but it's only for troubleshooting.

[emerygt350]

And yes, I couldn't find my electrical tape and covered the resistor with painters tape...

[Ishley]

I'm struggling with the same issues. I have a 270ohm and a 50 ohm in mine right now and I'm tweaking the MPS to get the AFR readings where I need them. I circle a few blocks in the neighborhood and I can tell pretty quick if I'm heading in the right direction. I have an AFR guage installed and an O2 sensor in the exhaust.

I'm running a new rebuilt 2056 with a webcam 73.

Today I went and reset the timing... and my engine seems to have lost some power and zip. I'm going to go back and reset my timing in the morning. I'm also running a 123 Distributor. It's been a struggle. After everything gets good and warmed up.... I go lean. The resistors have helped....but I'm not totally confident I'm there yet. I'm even more concerned about what happens in really hot weather.

[DC_neun_vierzehn]

Is anybody running one of these things?

https://www.ebay.com/itm/274663091106?itmme...vQAAOSw3PlgEuEF

[windforfun]

And how does that work?

[emerygt350]

That actually looks kosher. Just a pot adding resistance to the cht circuit.


On the timing front I have found in my 2056 with stock cam etc that 8 degrees advance was all I could add temp wise, advance disconnected. The engine wants 9. It just sounds, responds, everything better at 9 maybe even 10. Temps wouldn't allow it. I have the advance disconnected. Sadly I think the 123 dizzy doesn't have the finesse of the original retard advance analog fight the original dizzy had. I think it probably throws too much in and it makes the lean fight harder. So I am waiting till I feel good with my mix, then will add it back in later to see what effect it has.

I may just end up with a rich switch for long climbs.

[emerygt350]

I would also add that I tend to use hot highway 72 mph as my standard. That is where I see the issues. Around town I see benefits but there is never any concern about damage at less than 50.

[emerygt350]

Been A/B testing increased resistance today. I am up to 100 + the 250 and it looks pretty good. I could probably go just a hair more but the plugs are looking pretty good where I am. And I have put the advance back on. Seems to be fine now with the added fuel.

[r_towle]

Hot, same Steady rpm?
How is the fuel pressure at 72 mph steady speed?

I got a 2.4 to perform and behave, so it can be done with djet.

Rich

[emerygt350]

I put a boroscope on my fuel pressure gauge and put it through its paces, all good. 29lbs.

Yeah, my tests are done at 72, then I try it at 60, checking the plugs after immediate shutdowns. I have an AFR but I don't trust it much. It can tell me if I am richer or leaner than before but I don't have much faith in the number it gives me.

I have it set up with a 150 +the 250 for tomorrow. I want to see if I can go a little into the stinky rich range. So far I am not there.

I have found this more useful than tweaking the mps. This seems to behave better across rpms, throttle position , and vacuum level. I think setting the curve in the mps perfectly, richening to taste with the inner screw, then fine tuning with resistance might be the right thing, at least for this engine. I found the inner screw would give me rich spots I didn't want and barely nudged my cruising AFR (17-12inhg).

[worn]

That actually looks kosher. Just a pot adding resistance to the cht circuit.


On the timing front I have found in my 2056 with stock cam etc that 8 degrees advance was all I could add temp wise, advance disconnected. The engine wants 9. It just sounds, responds, everything better at 9 maybe even 10. Temps wouldn't allow it. I have the advance disconnected. Sadly I think the 123 dizzy doesn't have the finesse of the original retard advance analog fight the original dizzy had. I think it probably throws too much in and it makes the lean fight harder. So I am waiting till I feel good with my mix, then will add it back in later to see what effect it has.

I may just end up with a rich switch for long climbs.

Sounds so familiar to my 2056. Ran great towards stoichiometric, but too hot. I played a lot with potentiometers too. Then took on the fight against rust. Resealed the engine against oil leaks and while at it reduced the compression ratio to. Hope to be able to report soon.

[emerygt350]

I went all the way to 200+the 250 today. Played with timing (left the advance hooked up all day), gave it a little more on the inner screw, etc. even took the shield off the fan intake (stole it from a bus motor). I had a brand new O2 sensor I put in today as well. I was running 12.8 to 13 at cruise. Never went over 400, tends to sit at 375 up and down small hills at 72 mph 3200rpm. Cools rapidly on down hill. It was a cool day today though, 45 degrees at the warmest. Oil was great all day till I dropped the timing to 7, then the oil warmed a little. Put it back up to 8.5 and the oil came back down. Didn't change cht much. Extended long hill sat me steady at 394 (fighting a strong wind too). Cht from plug on cylinder 3 of course.

I may just have to suck it up and deal with it. Maybe I went a little higher than the 8.6 I calculated for compression. Probably get to the Dyno next week.

[r_towle]

It’s been a while, but I did get a 2.4 to work.
I tried every MPs ever made, ended up back with the proper 914, though I set it up for my engine and tune.
Djet was in more than the 914, and the MPs are all a bit different.
The Volvo p1800 ES MPs was very rich.
I remember using a POT (volume knob) in the CHT circuit while watching an 02 sensor live while driving in different condition's

It was a combination of CHT and mps, raising the FP a bit to get it slightly rich, which was the goal.

This was….2004, and it was a race/autox toy, and still is out there racking up the miles with no drama.

It took me a while, but once set it was done.


Rich

[emerygt350]

Yeah, the only place where I have an issue is 5th gear interstate travel. Racing it stays nice and cool. I may just have to make some kind of fudge for that and stop worrying about it.

[r_towle]

I took my personal engine to 2.6, back to carbs and a better camshaft.
I’m changing to ITB and EFI, with fully tunable settings….because it’s time

[emerygt350]

I took my personal engine to 2.6, back to carbs and a better camshaft.
I’m changing to ITB and EFI, with fully tunable settings….because it’s time

Yeah, since I just did a quick top end build the cam wasn't an option. When I go deeper next time I will definitely upgrade the cam, that is probably what is causing most of my problems at cruise. I have heard they run hotter than they should due to the exhaust timing I think.

[r_towle]

djet needs a certain camshaft...though you can go slightly more aggressive.

I will warn you...once you change the camshaft...$$$$ must follow.
Its a big costly decision...

Or...enjoy it as it is, which is cheaper and competitive against others in the same class.

Rich

[emerygt350]

djet needs a certain camshaft...though you can go slightly more aggressive.

I will warn you...once you change the camshaft...$$$$ must follow.
Its a big costly decision...

Or...enjoy it as it is, which is cheaper and competitive against others in the same class.

Rich

I think I would just go with that web cam or whatever I always see people putting into djets. Nothing fancy or high revving (mine already likes to blow right past the redline).

[emerygt350]

I added something new today. Leaving the resistance in my cht lead at 400ish. Will season to taste with the inner screw. However, now I have set up my little bluetooth switch to turn on and off a vacuum valve (EGR thingy from a Mazda) that allows ported vacuum to the distributor. Now, while cruising I can see what kind of effect the vacuum advance is having. Although I can see my vacuum on the gauge, it doesn't absolutely tell me if the advance is operating or not. Now I have to wait for it to warm up a little.

I also took this little snow interruption to actually install the bushing in the firewall for my shift linkage. I can't wait to try it. There was nothing there. When I pulled the motor I didn't even realize there was supposed to be a bushing there.

[emerygt350]

Cold day but I did feel temps were better without the advance. I am running a couple degrees advanced already (car just really likes it there) so perhaps it was just too much. Running really, really good though. Dyno is my next stop.