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knocks with stock base timing,runs better when increased

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Bastard1g

15+ Year Contributor
369
2
Nov 15, 2003
Jacksonville, Florida
I have the 6bolt swap with keydiver,pot mod and safc. 1g cas rewired among other things.
My problem is that at between 5-9 degrees, I see tons of knock and my car pulls back really bad. The only way I can drive my car is if I increase the base timing past a level of measurement. I have the cas almost maxed out. But it drives fine like that. If I set the timing to stock level, it knocks and pulls timing. I have the keydiver knock gauge so I can see where it knocks. Also, knock is a bit worse when I put in the bpr7es. I need them since I run 22 psi on pump gas. I am wondering why my cylinders are just not making the heat it needs? Doesnt knock under boost now either, if I try to put the base timing back to stock, it will knock at low and high throttle. Has a brand new oem coil pack. What do you guys think? Cas may be bad? I am stumped runs like a champ with no knock when advanced and retarded or stock base timing knocks and wants to die. My wb reads good and my afc is set right. 7:8:! compression ratio. I dont know what else to say.

I would also like to add that if my base timing is at stock level, I feel like there is a load on the motor. It wants to make boost way too early. fuel preasure is set right. All the lil things have been covered.
 
Correct me if I'm wrong, but it seems like you gave us the key answer to your question. With a compression ratio that low, you won't be making as much heat in the engine and as a result, you may trigger rich knock. If Jeff's chip isn't showing knock with the timing advanced then you should be fine setting it higher. The plugs are a giveaway too. If you were running 6's on an 8.5:1 motor and 22psi, it would be fairly awful, but the fact that you can run them on your setup and run the well indicates that low compression is the key.

I noticed that you don't use an AFC and although Jeff's deadtime compensation is right on, it may leave you a bit rich throughout the power band considering your compression ratio. Perhaps he can burn you another chip with an altered timing map, or if you prefer, you can just keep an eye on it yourself.

Hope that helps,

Andy

P.S. So tell me, does that 20G hit like a freight train when it comes in?
 
Actually I have the bullseye to4b vtrim and I have an afc correcting my high throttle to -21 across. A/f ratio is between 11:3 to 11:5 with no knock that I can see. The t04b hits hard though. It drives great now, but If I try to lower the timing back to stock or even near it, I get knock everywhere and I can feel my car pulling timing. I dont have an egt gauge so I am now just going by wideband and knock gauge. My friend logged my timing at wot a couple of days ago and I only got 4 degrees of timing but, since then I fixed a few boost leaks and switch to bpr7es. I will get on it more to see how it feels but It deff. feels better with more timing. Also, My cas is installed correctly, I tried to flip it around and it ran like total ass.
 
I see where you're coming from, but do you see how the lower compression really changes things? Also, why are the AFC settings so high if you have one of Jeff's chips? He should have been able to dial in the deadtime and global settings on your injectors so that you'd only need to correct for about -2% or so on the AFC.

Just wondering,

Andy

P.S. My mistake on missing the AFC in your original thread.
 
Well the low compression does sound like it may be the reason, but in that case, why do the 1g guys never have a problem with that? I just need to log my car now with more timing to see if I get any more timing at wot.
 
Well lets see here....

First of all, I would think that if you have to advance your base timing THAT much, something is messed up. You should not have to max out you CAS. You need to recheck you timing marks, cam alignment etc. If anything, I see people PULL base timing. Mine is @ 4 deg BTDC and it runs very well. And I agree that you should not have to adj. your AFC that much.

Also, where is your AFPR set to for base fueling?? You know that it needs to be set to where Jeff has it on the chip right?
 
Thats why I posted this question, I am wonering if my cam angle sensor is !@#$*??????

My cam timing is on, fuel preasure is stock 2g, A/f ratio is good. I double checked my cas and it is wired up right. I am running out of ideas, I would normally tell people to drop the timing but dropping the timing makes my car not even want to move. It seems like there is some sort of load on the motor. I dont understand why it knocks at stock base timing,but runs like a champ when advanced base timing.
 
In light of what I've just learned, then, yes I would recommend looking at the CAS and possibly the knock sensor as well. Sorry if I threw you off track as it seems you're heading in the right direction.

Let us know what develops.

Andy

P.S. This is something I'm not sure about, but when you swap a 6bolt, don't you need to lower the fuel pressure to 37-39? It's worth a look since the 2G's run 43 at idle.
 
The knock sensor is brand new from mitsu. As for the cas, its off of a 90 car, but It still works. I dont know if they just die or if they get out of calibration over time? Also, are they supposed to have play on the tip that goes into the cam?
 
I have done so much searching and still havent found what I need. I wonder if there is something that I am missing under the hood? It just doesnt make sense that I have to fire the spark so early to run decent. I need to find out if there is a pin on my ecu I can jump off to set the timing being that I have a 95 eprom.
 
Not to be a pain, but have you referenced the whole fuel pressure issue? If you're running 2G pressure on a 1G, that has to have some effect unless someone with more experience can happily prove me wrong. I'd set base pressure to 1G levels, correct the timing and see if it helps.

Andy
 
I'm a newbie but I would like to relay a story going back to my first starting to tune my car. I was asked if my timing was set correctly. I thought how could it NOT be correct. Well I need to take advice so i put the light on and it looked like it was set on 5* with the wire grounded. I remove the wire and the timing went lower!! It was supposed to go to 8*. It took about 10 minutes of thinking and trying it again when I realized that someone before me had the timing set on the WRONG side of the 10* mark so it was set at 15* base! Removing the groud wire did not cause the timing to go lower but to 18*. It was backwards! Iam NOT implying that my situation is a possibility here but perhaps some other guy reading these tuning threads will see this and check theirs.
 
Well, I found that the picture of a 90 style cas mounted on a 2g is very much like the angle mine is mounted. Still though, something is wrong because I can not drop my base timing without it running like total ass. Dropping my base timing will cause knock.
 
andymoraitis said:
Not to be a pain, but have you referenced the whole fuel pressure issue? If you're running 2G pressure on a 1G, that has to have some effect unless someone with more experience can happily prove me wrong. I'd set base pressure to 1G levels, correct the timing and see if it helps.

Andy


I have played with the fuel preasure but lowering the fuel preasure will lean my car out and that isnt the problem. My a/f ratio is right where I want it. My timing is screwed up for some reason. I cant find out if a bad cas would do that or not.
 
If you are currently trying to tune at 22 psi on pump gas I would consider backing the boost down to around 14-15 psi. Set your timing to stock. Reset the ECU.

One other thought. On my 1G when things really get out of wack the ECU will go into safe mode. I have a knock LED mod from wayyyyy back that lets me know then this has happened. It just shows the status of the BCS. Anyway, one time for kicks while the car was in safe mode (knock light steady on) I cranked up the timing and got the car to run pretty well. (until it came out of safe mode some time later) I suppose this could be a possibility to consider.
 
Well, I cant really turn the boost down witht his turbo, I run about 16 during the day and it spikes up to 20 at night when it is cold. I turned the timing up some more and it runs even better. It is more responsive and it pulls a lot harder. I need to borrow a logger from my friend again and check things out but I am also going to borrow my friends timing light to confirm my timing advance. From what I understand, to set the base timing on my car, all I have to do is match my cas timing with the advance shown on the logger. I still havent found out if a bad cas would cause me to have to run more timing to get the same power.
 
Who cares why it runs like poo with less timing.

You're blessed with something many DSM'ers would kill to have, aggressive timing with no signs of detonation.

In all reality,you could have a magically efficient head and intake manifold.
 
Well, I wont know if its good or not till later on in the week when I get the pocket logger hooked up for some more runs. With everything the same except for boost leaks, I was only getting 4 degrees of timing at wot. I would feel a whole lot better if I had an egt gauge but I guess I might get one pretty soon.
 
highly efficient motors and heads would not need much timing to burn fuel, on the contrary engines that require higher timing are inferior to those require less timing to efficiently operate. The fact that the EVO makes power with less timing(low teens) is evidence of a more efficient combustion chamber/piston/etc design and burn rate.

This is the main reason why you see early muscle cars running 35 degrees total advance, but a DSM wants much less. The mixture burns more slowly due to the early head designs. Modern combustion chambers produce a faster rise to peak cylinder pressure thus needing less timing.
 
My friend tells me I would be fine with 15-16 but 4-5 is too low. I have to fix my tb shaft seals before I can try to tune it again.
 
Did you figure anything out? Mine is doing the same thing.
 
I still havent figured it out. I am just gonna have to get dsmlink. There is no way that I can get this car running decent like it is. I am going to fix all the boost leaks and try to set the timing again but it is jacked up right now. The car just runs like ass. It bogs in the lower rpm's. I keep everyone posted on whats going on, I just have so many problems with this car that I never stop working on it.
 
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