installed new injectors, runs like junk

[kingearl]

I just replaced my stock injectors with my 625's. The car runs all the way down to -30% across the board on the AFC before it stalls but runs like junk unless its up around the -5% mark.

Anyway I set it up I have crappy acceleration until 3k RPM. I mean like hardly moving till that point. Then it takes off like stink.

Since I put them in I am getting way more knock. A bit more at idle, quite a bit more at normal acceleration and anything more then 11 pounds of boost send the knock pass 43 count. WTF!?

I wouldn't think the car would run so crappy just by installing these. What would help me out? AFPR? I need a new o2 sensor, I know that. But what is the problem mostly?

 

[brads]

First off, you said you were getting MORE knock at idle, and normal acceleration? Does that mean you were getting knock before the injector install?

The first things to check on the install would be mechanical, they are a little easier to find. First off, are you sure that each injector is seated properly, and that the seals that fit between the injector and manifold were in good shape when you reinstalled everything?

The second thing to check is just double check that the FPR vacuum line didnt come off when you reinstalled everything.

Brad

 

[kingearl]

Before I was getting 1 or 2 knock around 20 sec apart at idle. Now its twice as often. And I never got knock in neutral reving before, now it spikes to 11 at righ revs.

The seats looked fine. How would they look if they were not in good condition. Say, they were not in good shape, how would that contribute to this problem. Wouldnt they just leak or something?

No, the lines are all spick and spam.

 

[20gst]

I run 625cc I got from HRC. They have a good tuning chart to help you dial those in for starts
Ask HRC for 625 tuning chart to AFC. Or peek my AFC settings w/625cc and 20g set up

TH-30/80
Cr:+-15%
Lo-1000+2
1500+5
2000=0
3000-2
4000-5
5000-5
6000-5
7000-5
8000-5

Hi-1000-10
1500-15
2000-22
3000-28
4000-28
5000-25
6000-25
7000-25
8000-25

My EGT is at 900 at idle and at wot @3rd is 1400 and rising twords 1500.
I live in colorado so dont know how altitude will change the affects whare you live at. My O2 at wot around .91 Good luck.

 

[kingearl]

Well, that sure is interesting. I would think that your low throttle settings are extremely rich. But I guess anything is worth a shot. Thanks for the numbers, I'll give em a try.

 

[brads]

If the seal that goes between the injector and manifold is gone, then there would be a big airleak, and that could cause all sorts of problems with running, since the ECU wouldnt know about all that air getting in.

But if its all there, I'd start looking at your fuel trims. How do they look now, compared to what they were with the stock injectors? And you might want to look at your plugs too. If the injectors are mismatched, you will see it in the plugs.

Also, whats your base timing set at? When you added the injectors, and started pulling AF out to get the fuel mixture back in the right ballpark, you also started adding a lot more timing. If your timing was already advanced at the CAS, you would get loads of timing..

Brad

Originally posted by kingearl

The seats looked fine. How would they look if they were not in good condition. Say, they were not in good shape, how would that contribute to this problem. Wouldnt they just leak or something?

 

[brads]

If the seal that goes between the injector and manifold is gone, then there would be a big airleak, and that could cause all sorts of problems with running, since the ECU wouldnt know about all that air getting in.

But if its all there, I'd start looking at your fuel trims. How do they look now, compared to what they were with the stock injectors? And you might want to look at your plugs too. If the injectors are mismatched, you will see it in the plugs.

Also, whats your base timing set at? When you added the injectors, and started pulling AF out to get the fuel mixture back in the right ballpark, you also started adding a lot more timing. If your timing was already advanced at the CAS, you would get loads of timing..

Brad

Originally posted by kingearl

The seats looked fine. How would they look if they were not in good condition. Say, they were not in good shape, how would that contribute to this problem. Wouldnt they just leak or something?

 

[kingearl]

Ok, I tried all your settings and they worked very well for a while. So I thought I would up the boost to 15 psi. I know its not much but it was at 11 and I thought "baby steps". Anyway, not only did it not hold and forced the knock past 43 but the car ran like crap from then on.

I did some logging but it can be simplified to: push down throttle, knock increase, timing eraticly decreases.

The good news is I think I might know why this is happening. The seals on an injector.

-There is an o-ring at the top where the fuel from the rail goes in.
-Just below that o-ring there is a softer rubber seal.
-Where the fuel leaves the injector there is the harder seal that goes between the injector and manifold.

Are these three seals ment to be on all injectors? Stock AND aftermarket? My aftermarket injectors didn't have the soft rubber seal below the o-ring. Are they supposed to? Could this be causing a leak?

 

[nowayout]

how isyour o2 reding.

my o2 went bad and i was getting knock at part throottle an low rpm.
replace the o2 sensor made world of diff. the ECU can react correctly.

 

[kingearl]

I dont even bother with looking at the o2 readings because I know they are way off. Its an 11 year old sensor that has been through alot of crap. I am going to replace it soon.

I know this problem is not o2 related because for the most part everything was great up until last saturday when I put in the injectors. So I am going to rush take them out and try again after work. If anyone could confirm that I should have the softer rubber seal on my new injectors that would help me out.

 

[kingearl]

okkkkkkkkkkkkk, well, I re-installed them. Aftermarket dont have the seal in the middle I was talking about. And it didnt fix anything anyway.

Whatever, I will figure it out.

 

[kingearl]

This is pissing me off. Replacing the coil pack helped low RPM knock. The plug to Cyl. #4 was damaged and the spark was traveling to fuel rail. But anyway I still cant even run stock boost without topping 20 knock, anymore than that and it tops 43 counts. Its not that I am running rich because I tried it as low as the settings will go before it runs to the point of stalling and went up three points at a time to +7.

And on top of that, for the first time ever I got boost creep. No matter what I do the thing runs like crap according to the datalogger.

I am just venting, for anyone who may care......................

I'm sure I will figure it out.

 

[brads]

Sorry to hear its still giving you problems. Have you checked your fuel trims? How do they compare to your fuel trims before you swapped injectors? What about your base timing, have you checked to see where that is set? What 625cc injectors are they?
Are they definitely the right type(low impedance) for DSMs?

 

[LandoAWD]

Have you stopped to consider the basics...timing, knock sensor, ECU, lifters...how are all these?

 

[kingearl]

The injectors are low impedance. I checked myself to be sure. The mid and high fuel trims are always within 10% of 100. It seems it doesn't matter what I do they are always good. The low trim is always at 140%. I know this is not good but I cant lower it. I think this is because of my secondary intake tube on my intake. You know, the type that Dejon Tool sells to have air bypass the MAS. Just so you know, I always had this installed. Even back when everything ran great.

base timing at idle? Its 8-11.
knock sensor.......................... I dont think anything is wrong with it because like I mentioned before, replacing the coil pack brought the low end knock down alot. And I never had problems before.
ECU? What could be wrong with that?
Lifters are fine. I never had a problem with them, and since I have only had my car back for about a month and a half since the rebuild they would still be good anyway.

Thanks for the help.