The old warm up miss is back at 164 degrees ECT by the sensor down in the block. At the head the temp reaches 185 at this point. It misses with a jerky stutter. At its worst, the AF ratio will do random spikes up into high lean numbers,but I suspect this is from unburned fuel resulting from misfires. So I am now focusing on ignition, not fuel. Fuel pressure remains steady, and ignition counts stay steady on the RPM gauge, indicating the distributor is likely working fine and delivering its signal to the ECU correctly.

I am playing with the idea that a temperature differential between then intake manifold and the head makes misfires more likely at this temperature. This is new (or rather returned) since the weather got cold. The other thing that changed; I installed Charlie S's very short spark plugs to try and reduce detonation. So I have colder intake air, and a shorter electrode. This all worked fine as long as the weather was warm.

I have ordered new spark plug wires and am thinking of re-installing the extended tip plugs just to see if this solves the warm up drivability problem. It never feels like it will die as it did last year at this time, so things are better than they were. It just jerks and bucks until the temp gets up to 180 in the block, then it smooths out. It still does not feel quite as good as it did when the weather was warm.

There is a tuning screen for modifying things based on the difference between the head temp, and the manifold temp, but there is nothing in the manual that gives you a clue as to how this effects the driving of the car. I don't know how to tune it.

Another thing here is that with the 195 thermostat, it is as if the thermostat never opens if the temp does not get up to 195 at the head. Am I right about this? Toight the head temp gauge never got over 185,so i assume the thermostat is likely still closed.

So how can I get this to warm up faster? Would it work to put cardboard over part of the radiator in the winter? The heater works like a champ, so it is at least circulating there. I dont; know if a closed thermostat will restrict the heater flow. I was trying to imagine a device I could work with a choke cable that would close over part of the radiator. It is a large cross flow aluminum radiator. Thanks for any thoughts here. I am not feeling so discouraged as I was last year. I have learned alot, and can tell with my fuel pressure gauge and the good AF ratio gauge that the fuel seems to be working right. And I feel like I have something to try now.

Sam

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Sam, I don't know much about your fuel injection system offhand, so some of these questions are shots in the dark. They are what I would start looking at when faced with this symptom on a factory EFI system.

This jerky stutter, does it occur at all engine speeds and loads (idle, acceleration, etc) or is it specific to (or worse at) a particular speed and/or load?

Is this a mass airflow system (w/MAF sensor) or speed-density system (w/MAP sensor)?

Does this system use one or more air charge temp sensors? Where is/are it/they located, specifically?

Is this a closed-loop system trimming fuel by looking an O2 sensor once it's warmed up?

And, can you remind me where your intake air is drawn from?

Covering up the radiator, in whole or in part, is — at best — a way of covering up the symptom. It won't address the problem, and I don't think it'll have much effect on the symptom, either.

(And...what is the nature of your ignition system?)

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Sam, I did recall you had similar issues with this on Megasquirt as well?

Reason I ask is that it takes one to know one rather well to tell what is exactly wrong. Warmup miss can be anything: leaks, engine not *quite* warmed enough yet the computer thinks differently, small adjustment in the warm up settings needed for your situation where megasquirt really excels at because of very flexible settings for different modes of phases: cold starts, hot starts, warm up enrichment/enleanment etc.

The current box you are using and requires big bucks wide band sensor for particular EFI is the MAJOR reason I want to go with megasquirt stuff so I can choose and pick stuff to go with it.

Get the innovative WBO2 and start monitoring what your EFI and engine is doing when it misses as diagnostic/monitor tool.

Cheers, Wizard

Thanks for responding. To my recollection, I never had this problem with MS. Mega Squirt simply ran the stock distributor, and was fired by the output from the tack drive, as I recall. The reason for putting the cardboard over the radiator would be to help get the car warm before I get to work, so it would not be running cold most of it's life. That is kind of a seperate problem though.

I do have a wide band Innovate gauge. It is based on this and fuel pressure that I am working on the idea that the miss is not fuel ratio. The miss happens when the dash temp gauge, which reads off the stock sensor in the head gets to 180, and the ECT sensor for the ECU hits 164 which is down in the drain plug low in the block, as indicated on the lap top. The fuel pressure never falters. The MAP reading never falters. It all seems to be running along quite nicely, and the miss just hits suddenly, and rather convincingly. It is a major series of misses that feel like the engine could just quit at any moment. Backing off the throttle seems to help. It takes about 5 more minutes for the engine to warm up enough for the miss to go away. This happens when the ECT hits 180-185. Even after it warms up, it feels as if it might miss. Just a subtle feel, or suggestion of an insipient miss remains, if you know what I mean.

The ignition consists of a stock Mopar distributor with no vacuum or centrifigal advance. This sends the pulse to the ECU where it is read and interpreted. The ECU then, in turn fires the MSD box,which works in the standard way. I really suspect that it is possible that the distributor to ECU pickup is not as reliable as it could be. But, if it is missing tach counts, it happens so quickly that they do not show up to the naked eye. The initial problem I had with the Accel set up was it would not read the Mopar distributor at all. It just acted dead,with no RPM count during crank. I paid someone else to fix this, and all they did was rebuild the distributor, which I had already done with new parts. So I am not sure how they got it to work, since that fix was out side of my view at the time.

I could do a data log, except it would be difficult to drive, and run the laptop program at the same time; especialy since it would have to be started at just the right time in the warm up cycle. Now that I think of it, this mis was there in the warm weather too, just not so dramatically, and only in the higher RPM ranges, at the same ECT. It felt at that time like a miss from the timing being too advanced, so I was playing with the warm up advance schedule. That is completely tunable with the flexibility to take out or add timing at all ECT temp ranges.

I think I will tighten all the manifold bolts, and the TB mount bolts. Oh yeah, the intake air sensor is about 8" in front of the TB inlet. Sorry to be so verbose. Hopefully it will help anyone trying to figure out what is going on here. I sure wish I knew how adjusting the map for the intake manifold temp and ECT temp VRS ECT effects the way it drives. I suppose I could just try it, but you only get one shot at this as it is going through its warm up cycle.

Sam

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Can you give the ECU false information......

i.e. something like a variable resistor hooked up instead of the sensor so you can fake the inputs of the conditions that cause the problem.....

This should allow you to debug even if the engine is already warmed up...

(then there's always the possibility of falsifying the inputs to avoid the problem areas........)

I'm thinking there's some holes in the tables that confuses the ECU

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Ed
64 Valiant 225 / 904 / 42:1 manual steering / 9" drum brakes

I know it can be difficult to use a laptop for data logging while driving, but I'd try it anyway. Wouldn't it be possible to start the data log before the misfires happen and then comb through it later? Or does Accel limit your data log time?

At any rate, what I'd look for is a tach dropout - see if there's sudden downward (or, less likely, upward) spikes in the DFI's indicated RPM. These often show up if an ECU is having trouble reading your distributor sensor.

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"Mad Scientist" Matt Cramer
'66 Dart - turbocharged 225
My blog - Mad Scientist Matt's Lair

While you're digging around looking for the cause of the problem, rather than cardboard in front of the radiator, I'd suggest a house-current engine block heater.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

They are even listed on EBag right now and Dan has done business with the seller.
Really just trying to help
Frank

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Scrapple: Because a mind is a terrible thing to waste.
73 Duster - Race Car
66 Dart Wagon - DD
178" FED
82 D150
All Slant powered

Thanks for all your thoughts. All of you had some light to shed here. I think a block heater might at least make the combination of block and manifold temps happen with a different time pattern, which might shed some light on things.

I would be happy to put a variable resister in the ECT line to fake the conditions that are causing the misfire, if I knew what parts to buy specifically. I dont; have the electronic understanding to patch this together safely. I would be afraid of damaging my ECU with a bone head choice of some kind.

And, I suspect that there still might be something going on with the ignition read that could be uncovered by a data log. I will certainly get to that eventually if changing spark plugs and wires does not improve things.

I would like to improve the ingition eventually anyway. I would not be at all surprised if this part of the system has been a weakness from the start up, and was never brought truly up to speed. I am interested in learning what it takes in terms of education and hardware to put a better ignition trigger in the system. Especially if it lets me run sequential EFI. Since I knew nothing of efi when I began this project two or three years ago, I feel if I live long enough, and have enough help from my friends, I can get this next step done too. I know there are other systems out there that the Accel ECU supports which are better. Any favorites out there that you recommend I read about? How about the Ford EDIS? Any progress on the crank trigger? Would this be a magnetic trigger or Hall effect? Either are supposed to work with the Accel ECU.

Sam

Sam

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I'm just wondering if the problem might be simple. Condensation conditions under the distributor cap can be astoundingly temperature-specific...are you running a vented cap? Long-tip rotor?

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

That would be wonderful if it were so. I am not using a vented cap, but I am using a long tip rotor. Is there a part number for a vented cap. Can I just drill a hole in it?
Sam

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Get a Standard BlueStreak #CH410X.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thanks Dan. Do you know which parts chains might carry the Blue Streak line? BTW I went out and tightened all of the manifold nuts. They were all a little loose. Because I have the Dutra duals, I can keep them plenty tight without fear of cracking the exhaust manifold when it expands and contracts. They are quite hard to get to with all the turbo stuff, but eventually I was able to get some combination of extensions and flex joints on every one of them. Loose manifold blts can contribute to quirky warm up operation until the parts expand against each other. I think it can create a temporary vacuum leak.

Sam

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Ummmmm...not offhand, because I don't knwo what chains you have there. CarQuest would be a safe bet...

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

The coolant sensor need to be in RIGHT place, usually at the output where thermostat is (before the thermostat). Lot of makes I have seen always does. Even Tulip have this sensor right behind this thermostat on 2.2's head waterbox.

20F is BIG difference and can fool the engine computer thinking engine is still cold and affect the ignition curve and fuel mixture ratio. Lot of computers out there have set-point of 180F or just bit less. But not 160F.

The HOTTEST area is head and get the cooled last in the coolant circulation for that reason as you want engine to be at thermally efficient point.

Move that sensor!

Cheers, Wizard