low EGT values on specific cylinders

[alex d]

The guy where i took the injection system told me that the fact that i have one common throtthle plate per 2 cylinders is mainly the fact that i have uneven conditions between cyls and unstable idle... He told me that i cannot expect much with that setup.

there's probably ways to minimize the effect a little depending on the size of things, but yes, sharing the throttle plate for two cylinders with the firing order we have in a VW will always have some kind of these of issues

[andy198712]

So would a single tb fix this issue?

[lakis1982]

Martin,

in my previous posted picture of the engine, you can see a silicon hose (the left one beside the vertical tube) that is attached on the center horizontal tube.. THis is were my ECU's internal Map measures pressure from..

I am using engle FK8  and i dont think this cam could case bad idle..

i dont know how the car drives because i am still trying to setup the ECU... It definetily sounds much better when i reach 2000rpm(havent gone above that yet) but the EGT values even at 2000rpm still have major differences between cyl pair 1-3 and pair 2-4 as my videos shows... I cross check this by measuring the exhaust ports of the cylinders with a laser gun in order to make sure that it is not a matter of the egt sensors .. And as expected the laser gun shows 60c-70c for cylinder pair 1-3 and 170c-180c for cylinder pair 2-4...

[alex d]

I am using engle FK8  and i dont think this cam could case bad idle..

that would be true if you had individual runners....but you don't

[Martin S.]

I am using engle FK8  and i dont think this cam could case bad idle..

that would be true if you had individual runners....but you don't

<<This is a good cam for larger engines, with a powerband from 3000-6500 RPM max, it will idle a little rougher than stock with dual 2bbl carburetors, but is very rough with dual 1bbls.>>

The reason that engines run rough at idle is the overlap. These Engles are all 108 degrees. I have a Web Cam ordered specifically with less overlap for the EFI intake. (My engine guy thought overlap was stupid and people just want the sound  

Take it out for a drive and let us know how it runs above 2000 rpm.

(This is my cam card)
http://cal-look.no/lounge/index.php?action=dlattach;topic=10956.0;attach=80387

[lakis1982]

Hello,

Today I have replaced the spark plugs with brand new..and I operated the engine at 2000rpm for around 10 minutes..  the cylinders 1 and 3 temps as expected remained at low levels around 160C while on cylinders 2 and 4 at levels around 580C..but anyway I just wanted to posted a picture of the spark plugs exactly as they were after those 10 minutes of operation... Starting from left is the spark plug of the first cylinder and then of the second third and fourth cylinder in sequence..

So what does this picture makes you think as conclusion?

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[Martin S.]

Looks like 1 and 3 are not working at all. You said all 4 plugs were firing. Double check that.
Otherwise the injectors are not firing. Since you tried switching the injectors it could be the injector wires.
Can you monitor the injectors on the ecu? Try listening to each injector while running with a screwdriver or stethoscope.
Can you try a new file from a different person or source? Maybe yours is corrupt.

[richie]

Those plugs are wrong heat range for a normal street engine and will foul really easily, a NGK dpr 7ea would be a better choice & it does look to me like number 3 isn't working at all and number 1 hardly at all either
I would be trying for 0.90-0.92[13.23-13.52] lambda for gasoline/petrol once engine is warm and all cold start corrections are off[0.89 lambda would be ok still and shouldn't foul plugs]

[richie]

Also you said you haven't fitted a lambda sensor yet? so if that is correct then the lambda tables are worthless until you do, it cant tune if it doesn't know what the number are

cheers Richie

[andy198712]

is it batch fired ignition? guessing if so 1 & 3 are paired.....?

wasted spark from a single coil or again, paired COPS?

[Martin S.]

Here are pics of my last 2 sets of plugs. I?ve run DPR9EA (pictured on the left) and DPR7EA (right) with success.
You need a good ignition for these to not foul of course, but I have never had either heat range foul on my street turbo in thousands of miles. Run whatever you feel is necessary.

[lakis1982]

Richie,

I have already installed the wideband sensor some days ago.. you can see it's functioning in the YouTube links of my previous posts..

Andy,
Yes it is batches fired and it fires in pairs .. cylinders 1 and 3 together, and then cylinders 2 and 4 together as well..

Today, I tried the installed again the same spark plugs that I showed in my post yesterday, and let the engine run at 2000rpm.. after the engine was warm so that no extra corrections were applying but only the fuel correction due to wideband sensor, I started unplugging every injector..

When I unplugged injector 1, the engine started dropping rpm and it showed that was affected significantly by the fuel that was absent on cylinder 1.. the same behavior occured when I unplugged injector 3...if the injectors 1 and 3 were not functioning, then normally when I unplugged those injectors , I shouldn't see any major differences in the behavior of the engine, right???

Also, after this test and with the engine still running at 2000rpm, I started unplugging the spark plug leads.. when I unplugged the lead  from cylinder 1, the engine's running behaviour was affected significantly.. the same happened when I unplugged the lead from cylinder 3...obviously if the spark was not working at all on cylinders 1 and 3, I should not see any changes in the running behaviour of the engine, right??

At last, I continued running the engine at 2000rpm with everything plugged in , and increased the values of the VE table in order to create a rich condition , quite rich that the wideband could not correct.. my purpose was to see if that rich condition would make the spark plugs 1 and 3 to get some colour...

I did run the engine in total for around 20 minutes and below you see a new photo of the spark plugs after these 20 minutes.. no changes at all compared to yesterday's photo...

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Your conclusions???

[andy198712]

Are the plugs (1&3) wet with fuel? (Can?t see from the picture)

[lakis1982]

No all spark plugs were dry after we took them off..

[Martin S.]

?wasted spark from a single coil or again, paired COPS??

I was wondering this too. The ignition is hidden behind the shroud. The 1 and 3 problem is just too obviously related.

[lakis1982]

Hello..

In this image you can see my coil pack..
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What do you mean with"  paired COPS" ?

[lakis1982]

I have finally managed to change my single barrel throttle bodies to dual ones.
Quite happy about that (my pocket was not) because:

1. The engine completely transformed to a well idling and responsive engine. Now it behaves like an engine where all 4 cylinders are participating to provide power
2. The EGT values  are now quite close together even though I haven't started fine tuning the ECU parameters..

https://youtu.be/HHeC-M0dnho

3. They look much better that the previous ones..

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Thanks for pointing me to the right direction..

[PPRMicke]

Hello
I would think your ignition energy is too small for that mix
You can try to reduce the distance of your spark plugs to 0.20 (if it works with it you can change coil)
Have had a similar problem with a golf that had wasted spark coils
Then the limit was 11.6 AFR
Then I injected into an injector tester so and checked such Should you not be able to buy certain types of injectors about those with three holes For them can be very different
One thing that you can test is if you have the same pressure in the system. If you do not have to put a pressure damper on it (such have many car manufacturers when using large injectors) (Volvo V60R Awd / V40 / Saab Viggen / Bmw M3 /Bmw m5/porsche )
/// `Micke

[Martin S.]

It?s cool you?re using EGT like your car is a vintage aircraft 
Congratulations on solving the problem and have fun with your tuning. Take your time. I?ve heard some people spend hundreds of hours tuning 

[lakis1982]

HEllo,

it looks like i still have another problem... around 4 months ago i changed my throttle bodies and indeed this directly changed the behavior and operation of the engine instantly as the EGT values were quite similar on all cylinders without digging further into my ECU settings..
All that time i fired my engine just a few times (not drivable) on the car lift and it was idling and revving up to 2500rpm OK..

So now its time i start tuning me ECU maps and going to the dyno...But yesterday i tried to fire the engine as it was the first time after installing the air induction kit (air filter and hoses) because so far my turbo was sucking air directly from the air. Last time i fired it was before christmas.
And i realised that two of the cylinders EGT values are quite low (around 40C) while the other two are increasing rapidly..

What I did:
I made around 15 trials trying several things and on all of them the cylinders 1 and 2 were working (high EGT values) while cyls 3 and 4 were having low EGT values. So under cyls 3 and 4 i could see the unburned fuel on the floor.
I continued a few more trials but now it was the cyls 1 and 3 that were working while the other cyls 2 and 4 were not...
THen i made a couple of more trials and initially for 10 seconds all of the cyls started showing increasing EGT values but while the engine was running suddenly cyls 2 and 4 continued increasing their EGT value while on cyls 1 and 3 the EGT values started decreasing down again.
THen again i made around 5 trials and again cyls 1 and 3 were having high EGT values, cyls 2 and 4 low..

So now this is quite weird.. All of the cyls worked normally during all those trials but never all of them together at the same trial except once that happened only for a few seconds..
The EGT sensors seems to be OK because on the particular cyls that showed low EGT values i could touch the cyls and they were much much colder than the others and also i did see the unburned fuel droping to the floor through the exhaust gaps.
All the trials i did were around 15 seconds duration.
I also checked the loom that goes from ECU to the ignition coil tower and the cables were fine.
I changed spark plugs
I switched spark plug wires between trials but it didnt change anything. Between two trials it was still the cyls 1 and 3 that were working and it didnt affect this.
My voltage reading while the engine is running is 14V
No ECU settings were changed since it was working with those some time ago.

Do you have any idea about that What could be the problem ??


Thanks a lot in advance.