318 mystery problem, somewhat solved!

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7dswinger

7dswinger

MOPAR's rule
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So some of you know that I've had a mysterious problem of getting crazy low fuel economy, 11 mpg highway last time I measured it and I've somewhat solved it by re-timing the engine and re-tuning the EFI system.
But I've inherited another problem. When I re-timed the engine it pulled well but now that I've re-tuned the EFI system, the go pedal just makes everything louder but not allot happens.
The engine's not bogging down or delay when you hit the pedal and power comes on, there just isn't any power there. Any ideas on how I can solve this or is this just how powerful a basically stock 318 is, as I've never had this thing running properly so I wouldn't exactly know :cheers:
 
Just a bit confused by this comment.

" when you hit the pedal and power comes on, there just isn't any power there."

You say you retimed and retuned to get better mileage. What kind of mileage do you get now?

As far as the 318? Well I owned a 69 340 Swinger and the next car I owned was a 74 Plymouth Duster 318. Both bought brand new and both basically stock with the exception of the 340 getting a dual point diss. When I hit the loud pedal on the 340 I knew it. When I hit the loud pedal on the 318 I just got bored waiting for something to happen. If you are tuned for mileage, then my guess is you got what you want.

Did the car have more power before you tuned it for mileage? What changes can you make re mixture based on throttle position and load?
 
It means that I also get bored waiting for something to happen haha.
I have no clue I still have to get my speedo hooked up again before I can test anything but I will shortly.
The car had more power after I re-timed it but before I set the ECU on the EFI system back to factory settings but I've got them back to where I had them before. It's the EZ EFI system. I can change cruise air/fuel ratio for when you cruising around town or the highway, I can set WOT air/fuel ratio for when you hit the gas it'll go richer and and Idle a/f ratio. I can set Accel fuel which is the same thing as the accelerator pump on a Carb for when you hit the gas hard.

Edit: It's also developed a problem after hard acceleration, it'll want to die on you if you don't hit the gas. I'm guessing it's a fuel problem but the PSI checked out on the regulator and pump so I'm not sure. You can hear it happen on my car here
[ame="http://www.youtube.com/watch?v=nsHrJCdG01Q"]GOPR0084 - YouTube[/ame]
 
I'm not too familiar with the fast system, but I do believe that it has to do a bit of "learning" while driving for it to fully dial in for your specific engine. Based on map, tps, and o2 inputs. If it's falling on it's face after hard acceleration, if it doesn't adjust fuel supply quickly enough, you may be flooding it. Or, it could have something to do with your IAC. If for some reason you're IAC is closing fully under WOT, it will take it a second to readjust for idle.

Again, I don't know much about the fast system, but those are two things to consider perhaps.
 
True it still hasn't run on the new tune for as long as the old one but's been a few days now so it should be pretty close but we'll see how works after some more driving, my favorite part of testing haha
 
When my 360 was running I had a similar issue. You would hear the engine rev up but no movement of the car. It turned out to be I didn't have the kickdown cable adjusted right. Im not sure if you would have to readjust it for the changes you made.

Does the trans feel like it is slipping?
 
n00blike said:
When my 360 was running I had a similar issue. You would hear the engine rev up but no movement of the car. It turned out to be I didn't have the kickdown cable adjusted right. Im not sure if you would have to readjust it for the changes you made.

Does the trans feel like it is slipping?
Click to expand...

X2 as a possible solution since I just went through the whole kick-down readjustment process recently and was getting the "no-go during throttling symptoms". As I slowly adjusted it closer to the sweet spot the throttle response would tightening up.
 
7D,

Sounds pretty stout. Do get a lot of black smoke after you come off the throttle. Like others indicated, that could load it up and cause your stumble. In real driving you may find it will act a bit different.
 
No black smoke when I come off throttle as far as I can tell.
I'll look into the kickdown tomorrow, didn't think of that but that's definitely a possibility. Should I shorten the take up in it or loosen it first?
 
Sorry not black but grey. When you hit the throttle and then after you come off I see smoke out the tailpipes as it comes back to idle. A pretty decent puff. I think this is normal to see some of this, but yours seems a bit extreme. I am guessing you are running fat still.

How is it driving?

Oh and re the kickdown lever. Where does the car shift normally. The kickdown is also related to the govenor. So if your car shifts out of 1st real quick even with a fair amount of throttle, the kickdown adjustment may only help so much. I have that issue with my 340. I will be putting a higher rpm shift govenor in.
 
It seems to shift around 1200 rpm but I haven't watched when it has but I'll see.
Makes more sense now, now it does seem to run fat at idle, I'll raise the idle A/F ratio making it leaner and see how that works.
 
Ok so after driving it for awhile to get the EFI "learned" there has been somewhat of an improvement but not a whole lot so there still is an issue somewhere but not sure where.
I've gone through everything in this car short of pulling any of the drivetrain parts out and looking inside so far and can't find anything.
So far this is what I'm running:
EZ EFI system, currently running at 13.8 a/f at idle, 12.5 WOT, and 15.1 Cruise a/f ratio's
MSD 6A ignition box
Blaster ss coil
MSD E-Curve dizzy, every things timed right now, it's running 16* at idle and 35* all in at 2500 RPM
72 318, I don't know what's inside but I have tested compression and it checks out great.
A904, Don't know the torque converter rating, 1st shift is at 1500 RPM, bogs slightly and then pulls
71/4 rear end with 2.75 gears.

Any ideas on what could be causing this problem here, it's been very elusive and I'm out of ideas here. Noticeable problems so far is that it overheats fairly quickly and it struggles when it shifts at 1500rpm, other than that everything's running well as far as I can tell.
 
Overheats Quickly------- To Much Intial Timing (16 seems like a lot for stock 318)or is it lean???
 
So I should set the initial timing lower then? I'll try that and see how it goes as it didn't like anything lower than that, should I raise the idle, which is at 750 right now, and make it richer? The problem is that it runs so rich if I don't have it really lean, 14.7 is stoic (equal amount of fuel and air going in) and I'm at 15.1 (leaner).
Could running it so lean cause bad mileage?
 
Sounds a bit rich to me. You want more like 15:1 at idle, 13:1 WOT and 16:1 cruise.

Does the dist have a vacuum advance unit? Does the FAST system support ignition control, or is it just fuel?

When you say it shifts at 1500 RPM that must be pretty light throttle. If should shift more like 4500 WOT assuming the stock 318 governor.

I think your overheating could be something else, 16/35 is not an especially aggressive timing profile for a stock compression 318. Generally retarded timing will raise engine temps more than advanced.
 
hm interesting. 15.1 at idle and 16.1 at cruise seems really, really lean to me but I'll see how it takes it. I'm guessing that I should keep raising the idle air/fuel ratio as I stand there till it starts pinging? I'm just worried about leaning out the cruise a/f too much as I don't want to hit the throttle and have it lean out too much and damage something.
 
I doubt it will ping at idle no matter what you do (within reason).

With a reasonable ignition system and our slightly archaic combustion chamber designs, 17:1 is probably about where you'll start to run rough due to lean misfire. 15:1 is pretty close to stoichiometric and should give you a steady "clean" idle. That is, CO and HC emissions will be minimized and enough fuel will be available for smooth operation.

I honestly don't know a lot about the FAST systems or which one you're running My experience is mostly Bosch Jetronic (eurocar) and Rochester TBI (simple, hackable, effective, CHEAP). But I'll pass on a couple tuning thoughts I have...

Idle tuning: Your computer GUI should give you a MAP readout and possibly an IAC % readout. Since the computer adjusts the IAC to maintain a specified idle RPM it's a little harder to set it like we used to with carbs. In the old days we would adjust the mixture screws for either highest vacuum and/or smoothest idle. You can unplug the IAC motor and still do this (you've disabled an electric screwdriver on the throttle plate screws) or, you can make changes and see how it changes IAC open %. If you unplug the IAC motor start a bit rich like 13:1, unplug, and lean in steps until RPM or MAP peaks and begins to drop (50 RPM drop from peak was considered "lean best idle" when these cars were new, and works well now). If you can monitor IAC open % lean until the IAC motor begins to open and call it good. Either way you're basically homing in on the engines "sweet spot" much like old school vacuum gauge and by ear tuning.

Acceleration: Best power and detonation resistance is around 13:1. Anything much above this is wasting fuel and shortening ring life. Don't worry about leaning out under sudden acceleration. There should be an "acceleration enrichment" or some such algorithm in the software. This is basically a throttle pump. It recognizes rapid TPS opening and momentarily biases the mixture richer. Monkey with this last, just like pump shot, generally less is more.

Cruise: Much like idle, you're looking for the sweet spot. You can't look at IAC % so you need to look at MAP vs. RPM. Start somewhat rich, like 14:1 and lean to peak. You should end up at 16-17:1. Keep in mind that a leaner mixture likes more timing advance, so adding advance to higher MAP tables can be of great benefit. This is what a vacuum advance does. If you have spark control, you should be able to bias a table for this.

Reality check: my old totally stock 72 318 Dart (PS, PB, AC, AT) got 18-22 MPG. As I modded it with Carter 9636, LD4B, 340 cam and 2 1/4 duals I always maintained this. This should be your goal, and it's easily achievable.
 
I've got a handheld that gives me everything bit of info on the sensors which is great.

If I disconnect the IAC motor it'll give me an error and won't work I do believe, I may be able to pull the motor out of the throttle body, leaving it hooked up I think that should work. I'll try that.

Acceleration: There is a setting, call "acceleration fuel" on it that I can adjust. It's at "00" right now which is the base setting, I can set it negative for less and positive for more when you hit the throttle. I'll leave it there for now.

Cruise: That's much leaner than what I have been running it so that could be it, (hopefully haha) How much advance would you say it should be generally speaking? I've got around 16* initial at idle at around 35* all in at 2500 rpm with 10* of vac adv. The vac. adv. is on a slower curve then some others so I can speed that up.

I am worried about the overheating issue though, leaning it out more is going to raise the temp of the engine right?
 
So I tried the idle setting like you said and can't seem to make any effect on it. I disconnected the IAC motor, no error luckily. put it to 13:1 and then began raising it but as soon as I changed it the MAP began to go lower, do I keep going until the map gets as low as it will go and then starts going back up?

I go it to 15:1 for curiosities sake and it won't idle at all there, sputters and dies. Also the RPM will increase and decrees in a rhythm occasionally, not quite sure where that's coming from.

Edit: ok so I got it to run at 14:1 at idle but I had to raise the idle rpm from 750 to 900 and there's a noticeable low popping coming from the exhaust. Also the IAC is at like 40% when it should be at 20 at idle, there is an idle adjustment screw though, but I don't know if I can use that with this.... Idle is still erratic though, rpms will raise and lower a bit and it isn't very smooth. I'm going to try advancing the initial timing to and see how that helps. Any tips c130?
 
Advancing the initial timing didn't help, the rpms will keep increasing and then decreasing again and again, can't seem to stop it.
 
No, it sounds like it wants to be richer than I would have thought. Assuming your O2 sensor is accurate. Triple check the grounds on everything, at the low voltages involved, it doesn't take much resistance or noise to wreak havoc.
 
I called Fast about it and that's exactly what they said, there's a way to check it, 5 or below on the reading is ok for noise but mine was like 120 haha. So I picked up some materials and I'm going to re-route some wires from the ignition away from the EFI system.

O2 should be, I've checked for exhaust leaks and haven't been able to find any. If all else fails I'm going to call Fast again and see what they recommend.

Whats interesting is that when I run it rich like it seems to want, you can smell it it's so rich but when I raised it up it doesn't.

The constant revving of RPMS isn't a constant problem though, it comes and goes, it goes more than it comes but when it comes it causes the engine to die quickly.
 
Ok so I rewired allot of stuff so that there where no ignition wires around the EFI harness. Now everything has gone down hill somewhere. I've gone through all my connections and everything looks good, everything has power and proper grounds. It'll idle ok but when you hit the gas hard it'll bog and die and then there is loud buzzing noise seeming to come from the MSD 6A ignition box. Any ideas here? I'm going to back through all the connections and grounds again tommorow as it's getting to dark now but I've this buzzing sounds happens every time it dies when you hit the pedal.
There is also this, am I burning oil here like crazy or is this normal?
[ame="http://www.youtube.com/watch?v=lghuOBvxLBY&feature=youtu.be"]GOPR0085 - YouTube[/ame]
 
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