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Air/Fuell ratio Help

2K views 21 replies 9 participants last post by  HybridKid 
#1 ·
I recently upgraded to a DCR ignition coil & wires & now my a/f is a little off. With my oem coil & wires my a/f was low to mid 12's (in the summer) & now it's around mid 13's. Haven't drove at all this winter tell today so I'm thinking it could be the weather. Currently have my plugs gapped at .032 & runs on e85 with a bws turbo (incase it matters).
Pretty new to the forum so take it easy on me lol
Thanks so much
 
#5 ·
During WOT. My idol & crusing is the same. Car was sitting for a good few months but it was prettying much out of gas. I went with dcr because I've herd great things. Think I might buy a OE coil mainly for backup & to see if it changes anything.
Thanks for the help everyone, really appreciate everything.
 
#7 ·
During WOT. My idol & crusing is the same. Car was sitting for a good few months but it was prettying much out of gas. I went with dcr because I've herd great things. Think I might buy a OE coil mainly for backup & to see if it changes anything.
Thanks for the help everyone, really appreciate everything.
They have some great products/services and they have some snake oil items....the ones that have been here for a while know the difference. They are big into re-branding things....at a premium.
 
#12 · (Edited)
That is even worst than you said above. I doubt coil and wire changes alone will cause this. So you need to start checking your fuel pressure for one. 10-11 is usually the sweet spot for these engines for a WOT 3rd gear pull. e85 is different? (Question for the e85 guys.)
Mods: 1025cc injectors, full built stock turbo (bws), dst, e85, & the basic bolt on
What are the fuel system mods, other than the injectors?
Have you data logged and I am assuming you have an e85 tune?
Max Boost?
Injectors duty cycle while this is happening?
We will need a Complete modification list to better help; cams, engine, fuel to start.
 
#15 ·
Engine is stock. Walbro 255 for pump. It's on 22lbs of boost. Haven't data logged. Have Custom e85 tune. Not sure what the duty cycle is. Also wanted to point out that the car was running perfect before the ignition coil went out. Been doing a lot of research & wanted to ask u guys if it could possibly be an o2 sensor, map sensor? Forgot to mention that I have no cat, straight pipe.

Wanted to say thanks to all of you for being awesome & helping out.
 
#16 ·
It's possible it can be an O2 or MAP sensor but I believe you'd be having A/F problems all over if it were the O2 and the ECU doesn't look at the O2 during WOT. Another possibility could be TPS, if it's not seeing full throttle at WOT it may not be sending the correct signal. Check for any exhaust leaks before the wideband if you can.
 
#17 ·
Ignition components will seldom impact the air/fuel ratio unless you have something that's not adequate to create spark under high load (boost), get a miss, and the computer reacts and changes timing and fueling. Data logging would be a great start and in addition to the other suggestions, you might want to check fuel pressure. If you're running a stock return-less type (dead head) fuel system with the bigger Walbro pump and don't have an '03 fuel rail with a Schrader valve you'd need to get an in-line fitting adapter to connect a pressure gauge.

A single bad injector would likely cause drivability problems around town. The manifold absolute pressure (MAP) or throttle position sensor (TPS) are the two main sensor inputs used for calculating fueling (along with intake air temp which shouldn't have that dramatic impact and would trigger a code pretty quick if dead and really off). The TIP sensor when it switches over and samples barometric (atmospheric) pressure it also another item that could impact fueling.

If you can data log and the wideband is showing normal air/fuel (A/F) ratios at light load and cruising and the short and long-term fuel trims (which are used to adjust overall fueling outside wide-open throttle (WOT) and also used by the computer as a reference for under WOT) are all fairly normal that means your stock narrowband O2 is likely reading accurately at light load so there's less chance the wideband sensor went bad.

If this exactly happened with the ignition part changes it could be coincidence or possibly you moved/touched/damaged a vacuum line or something in the electrical harness, but if you primarily touched the coil pack connector and not much else isn't very likely.
 
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#18 ·
First would like to say thank you to everyone for being so awesome. So I found the problem. There's a hairline crack in the intake manifold that goes all the way through so I need to replace it. Since you guys are experts I was hopping you can help me with one more question. I was planing on just buying a stock manifold but now I'm looking at ported Polish manifolds. My main thing is, if I buy a ported polish one would I have to retune my car? Really don't want to have to do that due to money. I just don't want my a/f ratio to be all over the place. But if I don't need to tune my car again I'm going with the ported polish intake manifold.
Thanks
 
#21 ·
I have some of this JB weld stick that I'm going to try just for a very short temporary fix. I will be getting a port and polish manifold. I've been looking at SDK Motorsport & they have a pretty nice manifold & they do a core charge so it would only be $150. Is sdk a good place to go to?
Also, since I'm still learning (everyday) I have a question for u guys. Will a hairline crack in the manifold cause the a/f to be out of whack & to run lean?
Thanks again for the help, you guys are the best. I'm so happy I joined this forum
 
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