Injectors causing misfires, what next?

**unknowna4** · 06-02-2011 09:44 PM

So I've been having some misfires and I narrowed it down to two of my 580cc (Siemens?) injectors. Should I send them off to get cleaned/flowtested? Buy new ones? Any other options? Thanks for the help!

**unknowna4** · 06-03-2011 06:15 AM

Anyone?

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**dubgli** · 06-03-2011 06:23 AM

how do you know its your injectors? what code did you get? I'm currently getting a misfire in cylinder 3 and i've replaced the fuel injector, but the misfire still occurs. If you really have narrowed it down for sure the fuel injectors, then just send it off to be cleaned. It should only take a day or two and cost about $30 bucks each injector. Or if you don't want to wait, just buy 2.

Yes, as you stated above, those are your only options if you truely narrowed it down to the injectors. if you're ambitious and want to get your hands dirty you can try to clean them yourself. You will need some hardware, but its all relatively simple.

**unknowna4** · 06-03-2011 07:45 AM

Swapped the injectors around and the misfires followed. I've read something about these injectors spray patterns not gelling so well with our cars. If I do buy new injectors does anyone recomend me buying different injectors? If so any suggestions? Thanks

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**dubgli** · 06-03-2011 08:04 AM

i would definitley switch injectors. the 580s you have are narrow single cone spray and low impedance as well. Our 1.8t wants the total opposite, dual cone spray and high impedance. switch to 550s since they're close or just go bigger with 630s. What is your setup? tune? That will dictate which injectors you can run.

**unknowna4** · 06-03-2011 08:08 AM

GT2871r, Retro fitted return fuel line system, GIAC custom tune.

**dubgli** · 06-03-2011 08:31 AM

so i guess which injectors was the custom tune dialed in for? if it was specifically for the 580s, then i think you could go up to the 630s with minor tweaking. I don't know too many people if any at all that run the 580s..

**unknowna4** · 06-03-2011 08:35 AM

It was specifically tuned with these injectors. They're actually the 3172:
Coil Resistance: 12 Ohms / High Impedance /

Are these the 550cc?

**dubgli** · 06-03-2011 08:55 AM

yes, from my knowledge, the closest size injector to yours that are high impedance would be the 550s. And what do you know, there are some forsale in the classifieds under the b5 section.

**unknowna4** · 06-03-2011 09:12 AM

Whats peoples opinions on running siemens 630s? It will cost me the same to flowtest and clean these in the time I need them by as it would to buy the 630s

**dubgli** · 06-03-2011 09:58 AM

i think if you do a search on them, people use them interchangeably. I have them right now and they work fine.. I'm dealing with a misfire in cylinder 3 which i thought was fuel injector related, but i guess it is not. Many people use the 630s in place of the 550s.. Do they tweak? I would think so.

**unknowna4** · 06-03-2011 10:06 AM

Originally Posted by dubgli

i think if you do a search on them, people use them interchangeably. I have them right now and they work fine.. I'm dealing with a misfire in cylinder 3 which i thought was fuel injector related, but i guess it is not. Many people use the 630s in place of the 550s.. Do they tweak? I would think so.

My only concern is that this car was completely custom tuned by GIAC with this setup. Does GIAC tweak? With the history of the car I don't think so, I bought it used with this setup and there was some debacle with the tuning and apparently its not even a 100% finished file and it doesn't look like it ever will be.

**AudiA4Turbo22** · 06-03-2011 10:08 AM

I'm running the same file you're running and there is an update. However, I have the EXACT SAME ISSUE with my 550s. I noticed that my car is sucking in air from the fuel rail.

**unknowna4** · 06-03-2011 10:11 AM

Originally Posted by AudiA4Turbo22

I'm running the same file you're running and there is an update. However, I have the EXACT SAME ISSUE with my 550s. I noticed that my car is sucking in air from the fuel rail.

You done got tonys file from GIAC? Nice:) Didn't think it would ever see another car. (how did you get your hands on it?)

Yeah I'm thinking about switching to the 630s, maybe I should give GIAC a call and ask what they think

**AudiA4Turbo22** · 06-03-2011 11:10 AM

Actually I have Jeff Lee's file, it was tuned for a 3071R and I'm using it on my 3076R. It was designed for the 580 Siemen injectors, but I decided to use the Bosch 550s. I do however use it with a rising rate fuel system so that may be different in comparison to your file. I can't go over 5k, it misfires like an M16 with a stuck trigger.

**unknowna4** · 06-03-2011 11:43 AM

Originally Posted by AudiA4Turbo22

Actually I have Jeff Lee's file, it was tuned for a 3071R and I'm using it on my 3076R. It was designed for the 580 Siemen injectors, but I decided to use the Bosch 550s. I do however use it with a rising rate fuel system so that may be different in comparison to your file. I can't go over 5k, it misfires like an M16 with a stuck trigger.

Yeah this file was made specifically for tony's car and I'm pretty sure no one else has it. Thats crappy to hear, my car is really only misfiring at idle with my 580s. Looks like I'll be getting them flow tested and cleaned unless I hear back from GIAC today.

**unknowna4** · 06-03-2011 12:08 PM

So I talked to GIAC and they recommended sticking with the same injectors it was tuned for. Only problem is if these two can't be fixed the 3172s are discontinued and not to be found anywhere. What to do, what to do....

**dubgli** · 06-03-2011 01:06 PM

what i don't understand is if a fuel injector has a different or bad spray pattern, I would imagine that no matter how much of a custom tune you had for those injectors, it would still perform badly because the injector just isn't compatible i guess with the engine.

Maybe I have no idea, but that's just what i think. You can't tune wrong spraying injectors to work well.

**unknowna4** · 06-03-2011 01:22 PM

Im not sure if these are even the injectors others have problems with as those are low impedance and the 3172s that I have are high. Though they probably do have the same spray pattern. But the thing is the car ran perfect for a while

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**dubgli** · 06-03-2011 02:00 PM

ohhHH!!!! those.. yes.. i'm sorry.. i am mistaken then..

**unknowna4** · 06-03-2011 02:46 PM

Well I'll have the injectors back on monday after cleaning and flow testing so we'll see how that goes.

**unknowna4** · 06-07-2011 07:40 PM

Got the injectors back, they are all within a few % of each other, no real difference after the cleaning.

Now the misfires are occurring on 3 cylinders, not bad just at idle like before. If I turn on the A/C or the engine has any load at all the misfires go away.
It has new plugs, the misfires don't follow the coilpacks and they're not bad enough to throw any codes yet.

Any ideas?

Thanks

**unknowna4** · 06-07-2011 09:52 PM

Anyone?

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**unknowna4** · 06-08-2011 01:29 PM

No boost leaks either. What the frack else could this be?

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**dubgli** · 06-08-2011 02:00 PM

so you said earlier that you swapped injectors around and the misfire followed the injectors.. well now that you got them cleaned, swap them again to see if the misfires follow them still. i'm not sure if you already did this, but now try changing the plugs. AFter plugs, do coils. In my second post, i asked how you knew for sure it was your injectors because i had a similar incident and even though the misfire followed the injector, buying a new injector did not fix it.

**unknowna4** · 06-08-2011 02:46 PM

Yeah, I just put new plugs and coils in. Before the cleaning the misfires followed two of the injectors and now its misfiring on three of the four cylinders two of which have injectors that were on cylinders that were not misfiring before.

I plan on swapping the injectors again tonight when I get time, just checking to see if there are any other possibilities I can explore as well.

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**unknowna4** · 06-08-2011 02:52 PM

I assumed it was the injectors cause the misfire followed them. Did you ever get your misfire problem solved?

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**dubgli** · 06-08-2011 03:06 PM

well now that you ask.. i didn't do anything after buying the new injector.. it just stop misfiring eventually.. so maybe just clear the codes and drive again and the cleaned injectors will adjust or whatever.. (that may not be valid).. basically, just keep driving with the new injectors and it might fix itself..

i still suggest getting new plugs just to make sure.

**EBG 18T** · 06-08-2011 03:33 PM

How old are your coil packs? What is the gap on your plugs ?

**dubgli** · 06-08-2011 03:49 PM

OP stated new coilpacks i believe.. new plugs as well, but not sure on the gap.

**unknowna4** · 06-08-2011 05:12 PM

Originally Posted by EBG 18T

How old are your coil packs? What is the gap on your plugs ?

Brand new. F5DP0R at whatever they come pre gapped.

**dubgli** · 06-08-2011 05:22 PM

haha. that could very well be your problem OP.. never just buy plugs and install them. You have to gap them to .28. I guarantee they're not gapped to .28, but instead something wider and i bet they're all not even consistent with one another.. Either way, you have to gap those suckers. Try it and let us know.

**unknowna4** · 06-08-2011 05:27 PM

Originally Posted by dubgli

haha. that could very well be your problem OP.. never just buy plugs and install them. You have to gap them to .28. I guarantee they're not gapped to .28, but instead something wider and i bet they're all not even consistent with one another.. Either way, you have to gap those suckers. Try it and let us know.

Everything I've read about the F5DP0Rs is that you shouldn't touch the gap when you get them.

http://www.audizine.com/forum/showth...F5DPOR-Gapping
http://www.audizine.com/forum/showth...sch-F5DPOR-gap
http://forums.audiworld.com/showthread.php?t=1540269
http://audisrs.com/archive/correct-g...t__t_5747.html

Just a few of them, won't hurt to check though

**dubgli** · 06-08-2011 05:50 PM

oops.. sidefires.. okay.. you shouldn't have to gap those, you are correct.. but just check anyways, who knows.. i mean, you're checking all the boxes on the list and still getting misfires.. you've checked coilpacks, you have good injectors, and your plugs are new.. someone suggested i do a compression test when i had my misfires.. ??? maybe worth it?

**unknowna4** · 06-08-2011 09:40 PM

So I logged my boost and it's requesting 20psi but I'm only seeing 15 ish, leak tested it again and no leaks. wtf

**M-Hood** · 06-09-2011 07:51 AM

Originally Posted by unknowna4

So I logged my boost and it's requesting 20psi but I'm only seeing 15 ish, leak tested it again and no leaks. wtf

Can you post up the logs and are you saying the log is showing 20psi requested and 15psi actual?

When ever you have a misfire issue it is always a good idea to do a compression test of all 4 cylinders. It only takes about 5 minutes to do the test.

**unknowna4** · 06-09-2011 09:22 AM

Here are some logs

Raw numbers

**M-Hood** · 06-09-2011 09:30 AM

I would check the compression, then check to see if anything might be causing a flow restriction between the turbo and TB. Also check to make sure there isn't a flow restriction in the exhaust. If everything is good at that point you might want to check to see if there is an issue with the N75. It could also just be that the turbo just cant flow enough air to produce the requested boost or the WG rod has backed off a bit allowing it to be open when it should be fully closed. You can check that by unhooking the vac line to the wg actator or running a MBC/EBC to see if you are able to increase the actual boost.

What turbo are you running?

**unknowna4** · 06-09-2011 09:34 AM

Originally Posted by M-Hood

I would check the compression, then check to see if anything might be causing a flow restriction between the turbo and TB. Also check to make sure there isn't a flow restriction in the exhaust. If everything is good at that point you might want to check to see if there is an issue with the N75. It could also just be that the turbo just cant flow enough air to produce the requested boost or the WG rod has backed off a bit allowing it to be open when it should be fully closed. You can check that by unhooking the vac line to the wg actator or running a MBC/EBC to see if you are able to increase the actual boost.

What turbo are you running?

Thanks, I'll try doing some of these tonight. 2871R

**M-Hood** · 06-09-2011 09:39 AM

Best results with a BT or BAT are going to be with a EBC. So you might want to start looking at getting a good EBC. Its like adding a super computer to your N75 valve. lol
You can get a much sharper boost curve with the EBC then you can with the N75 which tends to ramp the boost to reduce spikes.

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