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Logging an Intermittent CEL ... Fixed Properly !!!

cheekychimp

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Apr 19, 2004
Messages
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Location
East Sussex, U.K.
Will a pocket logger only show a CEL code whilst the CEL is illuminated or will it record and store any CEL codes thrown during a journey?

I still have an intermittent CEL /ubbthreads/images/graemlins/frown.gif. I believe it may be associated with fuel contamination. I have had hesitation issues for some time and am working through cleaning the fuel system (may still have to pull the fuel tank to make things right).

CEL generally illuminates whilst coasting down to a stop. It will go out instantly the throttle pedal is touched again. Will do this under load and whilst idling in neutral. Tried blipping the throttle tonight and CEL would come on as revs dropped and remain illuminated at idle then go out as soon as the the throttle was touched.

Swapped in a known good ECU and the same problem. I have drained the fuel tank, put in fresh fuel, replaced injectors, fuel pump and fuel filter.

I don't have a logger so I haven't tried to log the CEL yet. I am willing to purchase a logger, it seems like a good move but I believe the ECU is dual board and I seem to remember a post about not being able to log non-EPROM boards. I do have an EPROM JDM ECU that is in good shape. I would just need a 510 injector chip to go in that to match the injectors or swap in some good 450s for now.

Any ideas what might cause this? ISC? TPS? Would a stealership diagnostic computer unveil anything a pocket logger won't?
 
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mitsu90

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Nov 16, 2005
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706
Location
Illinois
I know mmcd will show all CEL that have been until they are cleared. So I am sure pocket logger will do the same.
 
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SouthCaliVR4

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984
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North county San Diego
I have noticed on our cars the cel illuminates while the condition for the code set exists but as soon as whatever causes it to light comes back into spec the light goes out however, the code is still stored in the ecu. Just the other day I was surprised to find an 02 code when I went to log the system, I didn't recall having the light even come on. While logging my pulls I did see the light come on for a brief second & again stored a code for o2 circuit. In my case it was a rich run situation sending my o2 static but only at a particular rpm & throttle setting.

So I would think you'll be able to pull the code, light on or not, with a scanner, logger or by the flash method.
 

cheekychimp

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Apr 19, 2004
Messages
7,333
Location
East Sussex, U.K.
That is interesting. I'm beginning to think the CEL and the bucking issue aren't related. I had a clear run through the tunnel home late tonight without any other cars around and the CEL comes on religiously between 2900 rpms and 3200 rpms when coasting down in any gear. Once on it simply remains illuminated as rpms drop but goes out with the slightest blip of the throttle. I am at a complete loss. I get absolutely no accompanying driveability issues BUT when the car does buck it is also invariably around the 3000 rpms area so I am wondering with a full tank of fuel if the ECU is picking up an issue in that area that is going to manifest itself in hesitation and bucking when I get to the bottom of the tank and more crap gets pumped into the fuel lines.

I think I am going to have to bite the bullet, pull the tank and clean the entire fuel system to eliminate that as a source of interference and then deal with the CEL if it exists. I need to pull the JDM EPROM ECU out of the other car and get Ryan to check the configuration of the original chip that came in it. If it's 450cc, I'll just throw a set of 450s back in and get a logger setup and log it.
 

toybreaker

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Apr 30, 2006
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posting under the influence, not so good /ubbthreads/images/graemlins/blush.gif
 
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SouthCaliVR4

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Jul 31, 2010
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North county San Diego
/ubbthreads/images/graemlins/rofl.gif /ubbthreads/images/graemlins/rofl.gif /ubbthreads/images/graemlins/rofl.gif
 

curtis

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May 4, 2003
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11,892
Location
Clarksville TN
TB is up to no good again. /ubbthreads/images/graemlins/rofl.gif
 

Wizardawd

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Aug 7, 2007
Messages
1,323
Location
Franklin, NC
Try this CC, 1st, make sure your throttle cable is not too tight, loosen it a little anyways and see what happens. If nothing improves, unplug the throttle stop switch. Sometimes the switch will fail or get out of adjustment, etc and this

(1)Throws a TPS code which states: Even though the TSS shows closed, there is a value of over 2v at the tps.
(2)Will cut fuel at around 3-4k regardless of load because the ECU sees a closed throttle.

I had an issue with my 1g last winter during a snow storm. It would just buck non-stop. Idled fine, but couldn't drive it anywhere. Like a idle surge that only happened during throttle application. Unplugged the TSS and although the car idled high, the problem was gone. Apparently some wiring had gotten wet during the blizzard and was shorting the TSS signal to ground. And the same car was throwing a CEL for TPS today after I put a new cylinder head on. Turns out the throttle cable was a tad too tight.

Wiz
 

cheekychimp

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Joined
Apr 19, 2004
Messages
7,333
Location
East Sussex, U.K.
Quoting SouthCaliVR4:
I have noticed on our cars the cel illuminates while the condition for the code set exists but as soon as whatever causes it to light comes back into spec the light goes out however, the code is still stored in the ecu. Just the other day I was surprised to find an 02 code when I went to log the system, I didn't recall having the light even come on. While logging my pulls I did see the light come on for a brief second & again stored a code for o2 circuit. In my case it was a rich run situation sending my o2 static but only at a particular rpm & throttle setting.

So I would think you'll be able to pull the code, light on or not, with a scanner, logger or by the flash method.



Well you weren't far off were you mate. Thanks for the input guys, I did a few checks and even swapped in another MAF (good move because now I can take off the OEM airbox and convert it over to the 3G MAF before I get a chip). But this O2 sensor code sounded all too close to my situation and despite not being able to log it just yet, I figured a new O2 sensor never did any car any harm so we swapped one in.

FIXED.
 
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Wizardawd

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Aug 7, 2007
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Franklin, NC
Makes sense, glad you found it.

Wiz
 

cheekychimp

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Apr 19, 2004
Messages
7,333
Location
East Sussex, U.K.
Yeah, I am actually not convinced there isn't something in what you suggested as well Wiz. There is still something however slight going on at the 2500-3500 rpm mark right about where boost starts to cut in. Ken is going to find another TPS and closed throttle switch and swap that on to see if that clears it up. It flashed a CEL at me this morning twice but nothing the whole afternoon and evening. I wish I could get hold of Jeff. I'd have him do me a new chip as I was intending to do anyway and put that in the EPROM ECU and get a logger.
 

cheekychimp

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Joined
Apr 19, 2004
Messages
7,333
Location
East Sussex, U.K.
Well, it has been interesting diagnosing this and discovering lots of little things on the way. I am still amazed at people's insight into these cars and even though this problem finally seems to be fixed for good there are still a few things in the list above that I haven't checked but still intend to to ensure everything is working as well as possible.

I had a feeling from the start that some of what Wiz said was the problem. After changing the MAF and the O2 sensor the problem got better so I assumed we had solved it, but then it came back back with a vengeance. Anyway after some fiddling we decided that the problem was rpm and throttle related and we came to the conclusion that the throttle body should be changed out. As luck would have it Ken just took delivery of two 70mm aftermarket throttle bodies machined to take the stock Mitsubishi ISC, FIAV, TPS gubbins so he sold me one and threw on a different TPS sensor.

FIXED.

I can't discount Rich's suggestion that the filthy FIAV was exacerbating the problems we were having but I think the TPS sensor was seriously shagged. I have no idea if it had anything to do with the TPS being off but when Ken brought the car back he said it was much faster rocking the new Exhaust and the throttle body, but when I first drove it I thought it felt sluggish. After about 5 minutes I realized I just wasn't giving it enough gas. So I don't know if the throttle was responding differently before but as soon as I got used to it the car felt so much better! Ken also said he changed the spark plugs and gapped them properly. I can't remember but I don't think we ever checked the plugs before which was a bit silly.

But anyway the best thing is there is no longer any bucking, definitely no CEL and the car whilst being fractionally louder than before sounds awesome. The idle is a touch fast for me at about 1000 rpm. I'd like to maybe bring that down a bit but it is rock solid so all in all I'm pretty happy with things as they are right now. I'd like to fix the snapped exhaust manifold stud and the subsequent annoying leak it has caused and then fit an MBC and raise the boost a fraction to around 0.9 bar. After that I think it will be mainly cosmetic enhancements for now. We pulled the stock wing, drilled the trunk and fitted the GTS-32 rear wing tonight. Those are both going to the paint shop on Monday so they can match the colour and spray the R32 wing black. I have a rear sun visor to go on and Ken is digging out some rain guards for me and I'll be about set. I'd kind of like to do the seats leather too. Ironic isn't it that we all want what we can't get. You guys thing the fabric seats are cool and we think the leather ones are an 'upgrade'.

Anyways thanks for everyone's help. Like I said, I still intend to check the other stuff on the list we haven't yet got around too but at least the car is running great now.
 
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