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MikeD
*R/T*
11/11/2002
20:07:12
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 Subject: KRC Tech...Need Advice
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Hey Marty,
I got my truck on the dyno last weekend after the 24# injectors and the roller rockers finally went on. Well I had put the injectors on to help w/ the lean problem I had before the injectors. Well on the dyno it still said I was running really lean...its like I never even put injectors on it at all.
2 things I can think of...
1. I have a flash but granted I got that before the heads, cam & injectors.
2. When I cut all 3 cats off I welded the 2 front O2 sensors in but left the back 2 hanging and there's no katbox on my truck and I'm thinking the computer is seeing its running rich w/ the front O2 sensors but not reading the back 2 so its leaning it out.
Best Dyno # before the injectors
309 rwhp
317 rwtq
Best Dyno # after the injectors
306 rwhp
322 rwtq
Any thoughts?
~Mike~
Get In...Sit Down...Shutup...& Hangon
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KRC Tech
Dodge Dakota
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11/11/2002
20:45:35
|  RE: KRC Tech...Need Advice
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Whether it's the Kat boxes or whoevers' you should emulate that circuit. The PCM can think there is a failure and change fuel as it see's the cat is plugged. What you are seeing Mike is what I see everyday, weather. Your torque is up due to the injectors and the longterm fuel trim has made adjustments. I dyno in the mornings here before the sun hits the building, because the results can be as far as 20 off by the afternoon. Get yourself a hand held weather machine for the track or dyno and see what the altitude correction shows you. I am at sea level and sometimes the air density has a correction of 1400'. As for running lean, get yourself a better fuel pump which can save you from the reflash. That may be all you need to richen up the parameters of your current flash. I use the Holley intank pumps here, which are rated for 800hp. Later....
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???????
Dodge Dakota
JOIN HERE
11/11/2002
20:49:47
| RE: KRC Tech...Need Advice
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what kind of computer are you running?? if it`s stock that the problem. the computer wasn`t mapped for the extra air fuel. it doesn`t know that injectors are bigger intil you tell it so. when you left the downstream o2 sensors out did it trip the check engine light?? on my car they do . they read cat efficiencey.(is that correct spelling?) you can still over ride them by splicing quarter watt resister from radio shack forgot part# on one of the wires black i think i would have to double check?
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KRC Tech
Dodge Dakota
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11/11/2002
20:57:39
| RE: KRC Tech...Need Advice
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Believe me, simple resistors don't work for the circuit. Mike has a performance flash, but it was set up for 19lbs, correct Mike?
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MikeD
*R/T*
11/11/2002
21:02:25
| RE: KRC Tech...Need Advice
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Yes the flash was for a mildy modified engine...not was radical as I've got it now.
I heard the rear O2 sensors read the temp of the cats...do they do more? I know the front ones measure air/fuel mixtures...but do the rear ones read the air/fuel mix after it passes through the kat?
So the main fix would be the fuel pump or a katbox?
~Mike~
Get In...Sit Down...Shutup...& Hangon
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MikeD
*R/T*
11/11/2002
21:08:36
| RE: KRC Tech...Need Advice
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I was looking on the Holley site...
Do I need the 255lph Forced Induction pump?
~Mike~
Get In...Sit Down...Shutup...& Hangon
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??????
Dodge Dakota
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11/11/2002
21:14:14
| RE: KRC Tech...Need Advice
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if you cut the wire in half and sodier it in it works. a bigger fuel pump is wise but 800 hp pump how are you going to regulate fuel psi? 60 psi isn`t going to be wise at idle. if the resistance is matched to the resistor it will work i have done it! it only read cat efficienecy. you must cut the right wire on the sensor and place in resistor. the sensors sould be almost the same but, downstream has a coating protecting it from water, a by product from the cat
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?????
Dodge Dakota
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11/11/2002
21:39:50
| RE: KRC Tech...Need Advice
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i think your fix would be computer reflashed for add on`s. on your fuel rail there sould be a valve looks like tire valve hook a psi meter to it see what psi is and what does threw rpm if it goes down at higher rpms fuel pump is not up to the task. but i would upgrade it anyway 255liter/hour pump. cause horsepower is a never ending battle.are you done with up grades?
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?????
Dodge Dakota
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11/11/2002
21:41:22
| RE: KRC Tech...Need Advice
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i think your fix would be computer reflashed for add on`s. on your fuel rail there sould be a valve looks like tire valve hook a psi meter to it see what psi is and what does threw rpm if it goes down at higher rpms fuel pump is not up to the task. but i would upgrade it anyway 255liter/hour pump. cause horsepower is a never ending battle.are you done with up grades?
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MikeD
*R/T*
11/11/2002
21:41:49
| RE: KRC Tech...Need Advice
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Yeah I've pretty much done every add on besides a supercharger or nitrous...wanna keep it all motor.
Got an MSD box going on somtime this week to finish everything up. Maybe the fuel pump will be one more thing I gotta do.
~Mike~
Get In...Sit Down...Shutup...& Hangon
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?????
Dodge Dakota
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11/11/2002
21:47:21
| RE: KRC Tech...Need Advice
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wanted to know when you disconnected downstream o2 sensor did it trip computer?
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?????
Dodge Dakota
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11/11/2002
21:56:48
| RE: KRC Tech...Need Advice
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wanted to know when you disconnected downstream o2 sensor did it trip computer?
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MikeD
*R/T*
11/11/2002
21:57:02
| RE: KRC Tech...Need Advice
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It did a long time ago but I guess it learned it and it went away after awhile.
When you mentioned the fuel rail knob...does that have anything to do w/ the fuel pressure? Cuz when I changed my injectors I noticed it wasn't screwed down all the way like it still could be screwed tight.
~Mike~
Get In...Sit Down...Shutup...& Hangon
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?????
Dodge Dakota
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11/11/2002
22:04:43
| RE: KRC Tech...Need Advice
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no it sould be just like a tire valve it is a port for releaving pressure or to test pressure. you can unscrew it and look at what i mean (looks like a tire valve) scharder (spelling wrong) valve. good place to run fuel for nitrous. for nice wet 75 shot beware!!!
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?????
Dodge Dakota
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11/11/2002
22:07:37
| RE: KRC Tech...Need Advice
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no it sould be just like a tire valve it is a port for releaving pressure or to test pressure. you can unscrew it and look at what i mean (looks like a tire valve) scharder (spelling wrong) valve. good place to run fuel for nitrous. for nice wet 75 shot beware!!!
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KRC Tech
Dodge Dakota
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11/12/2002
07:02:44
| RE: KRC Tech...Need Advice
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Cat efficiency is not a simple resistance. It has to have a firing circuit. The 255FO pump will sit at 50 psi on the rails if you leave the intank regulator on, but the volume will go from 99lph to 255. But don't take my word for it, go ahead and try the simple resistor. Don't forget, there are two circuits to simm out in a single O2, one based upon reactive and resistive readings..if you choose to remove the regulator in the tank, the truck will run fine at 60 psi at idle with your 24fms, I do not recommend that for the stock pintle injectors. But like I said, don't take my word for it....
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graphiteRT
R/T
11/12/2002
11:15:41
| RE: KRC Tech...Need Advice
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Who did the flash?
The WOT tables would have to be pretty messed up if you've bumped the injectors size by better than 10% and it didn't register a change. Did you also check with the dyno shop to verify that they have a good, CALIBRATED wideband sensor? This is something I don't see many folks asking about, rather they assume that all shops understand the importance. Fact is, they get all types of customer cars in there, some of whom are running leaded fuel without telling them. Contaminated sensors will read slow or lean usually.
I wouldn't assume the fuel pump will correct the problem, especially if you still have the regulator still in place. You might think simply bumping the pressure will compensate, but the PCM factors in a fuel pressure offset in open loop which will effectively negate a good part of that. The factory pump, assuming it's in good working order, is good to 400 rwhp anyway(pers. comm. with DCX powertrain guy).
What year is your truck, BTW?
Bob
'01 Graphite CC R/T, MP headers, Magnaflow muffler into 'Cuda style exhaust, M1 2bbl, ported 2.02 R/T heads, custom grind cam, Crower SS rockers, Paxton Novi2000, Boyd's 20s w/Dunlop SP9000s
Soon: Viper 4 wheel discs
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MikeD
*R/T*
11/12/2002
13:38:34
| RE: KRC Tech...Need Advice
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Kenne Bell did the flash and I guess I've heard they aren't as aggressive as B&G who I heard advances their timing twice as much as Kenne Bell.
Guess you live & learn!
~Mike~
Get In...Sit Down...Shutup...& Hangon
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?????
Dodge Dakota
JOIN HERE
11/12/2002
17:38:20
| RE: KRC Tech...Need Advice
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listen your cats only read at light trottle at about 35-50 mph after truck is out of open loop mode and it doesn`t read all the time like 02. chysler has a patten on the system. if your truck hasn`t learned too fix itself, it has to do with the computer reprogramming, higher rpm speed limiter gone? the system will work if done right?? i have done it so any question talk to me. it only reads resistance, in ohms sucker.
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KRC Tech
Dodge Dakota
JOIN HERE
11/13/2002
07:22:42
| Fixin Ta' learn Ya'
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Alright Mr ???????, if you've done it,prove it. Tell everyone here how you did it so they can try themselves, instead of bragging about your knowledge and keeping it to yourself. Tell me this simple resistor that I only have to place across "one wire" and then explain how my 500+ trucks ranging from 93-2002 are going to "learn to fix themselves". Come on, share the wealth. If you are referring to me as the Sucker, then with all those ???????, you must be the Joker....Holy Kat Simms Batman!
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CW
GenIII
11/13/2002
09:30:53
|  RE: KRC Tech...Need Advice
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Glad you called him on it KRC Tech. Some trucks won't throw a light even when the cat has been removed. Doesn't mean that they run nearly as well as one with a O2 simm.
4.7 HO, CW style
2001 4.7 5sp 3.92 LSD
Ported 68mm TB, IAT adjuster, 3" flowmaster cat back, TPS @ .76V, 4" Z-tube, Roadmaster active suspention, Removed Third cat, Electric fan Convertion, HO cams, Robert shaw 180 therm, HO intake manifold.
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???????
Dodge Dakota
JOIN HERE
11/13/2002
16:45:49
| RE: KRC Tech...Need Advice
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what i said is that no pcm will learn to fix it`s self . on the sensor. what i did was to cut the wire completly and sodier in the resistor that matched it in ohms. if you have three wires from downstream sensor one ground, power, and pcm readout. that pcm readout is the one you cut and put the resistor in. the wire must be cut completly. the resistance should be in any good repair manual in ohms. so the computer gets the right readout in the range of a good sensor and doesn`t see the problem.
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dr0p0ff
DakotaEnthusiast
11/13/2002
16:50:55
| RE: KRC Tech...Need Advice
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?????? - have you actually LOOKED at a FSM?
"the resistance should be in any good repair manual in ohms"
no sir, REPAIR manuals dont tell you how to jerry-rig your $hit. forums do that
Keep On Truckin!
Sgt G
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??????
Dodge Dakota
JOIN HERE
11/13/2002
17:25:11
| RE: KRC Tech...Need Advice
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ok dumby what do is use a mutli meter to check it like any good car person should have. it will tell you the readout. remember to bring it up to temp. watch out for that tree!!
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KRC Tech
Dodge Dakota
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11/13/2002
21:48:21
| RE: KRC Tech...Need Advice
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You really do not understand that circuit, do you Mr ???????. It is a crosscount of milliseconds that the PCM reads. For example, .36 volts to .87 volts in a period of 22 milliseconds after warmup. The PCM counts the period and the range, second, it monitors the heater circiut feedback that the 12 volts supplies. One resistor ain't cuttin it, otherwize, us Dakota racers would have figured that out in 96'. The engineers knew that simple resistors needed deeper lines of code to keep guys like us from doing that old trick, therefore, crosscount monitoring circuits were created deep within the recesses of the SAE minds. Later...
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??????
Dodge Dakota
JOIN HERE
11/13/2002
23:08:34
| RE: KRC Tech...Need Advice
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i have done the fix just cause you anal boys don`t get it.
then why the fucck did it work in my vehicle. i got the part from radio shack and did it it works. krc tech where do you live at cause if you stay near detroit mi i would be happy to show you plus met my friend who helped write some of dodge pcm programs he knows more about it than you or i he is the one who told me how to do it(it works) if i had the part # you could do it yourself. i can`t remember PS he drive several prodotype dodges vipers, prowlers, turbo pt
i will look up part # and get back with you
(sorry about the bad language)
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??????
Dodge Dakota
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11/13/2002
23:30:26
|  RE: KRC Tech...Need Advice
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here it is 1 quarter watt 1 megohm resistor part # 271-1356 radio shack catalog. hook it up to the black signal wire far as you can from the heat so you don`t melt the sodier. make sure you cover it with shrink tubing. IT WORKS!!!!! CAT BYPASS CAT BYPASS CAT BYPASS SING IT CAT BYPASS CAT BYPASS NOW GO DO IT AND CALL ME A LIAR. where is a will there is a way.
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KRC Tech
Dodge Dakota
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11/14/2002
06:59:31
| RE: KRC Tech...Need Advice
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Okay Mr ??????. I spent yesterday and last night wiring in another custom harness for the Fel-Pro FAST system, seeing that all my leads were exposed, I tried it this morning, and it failed in two minutes with the heater circuit. Then the cat effieciency code set.
Second, the 0.25 Watt burnt up, generated too much heat for that size. This was installed at the PCM connector, nowhere near any heat. Would you like me to try seven more trucks too prove you are being misled? If you truly believe the post cat sensors only look at cat effiecency, then your friend who knows more than anybody is misled also. Florida, bring it on down..I can guarantee that the fuel mixture on your truck is off.....speaking on that, what is your truck and what year? Make sure we are talking apples and oranges here.
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??????
Dodge Dakota
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11/14/2002
15:39:35
| RE: KRC Tech...Need Advice
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RT 99, 98 ram 5.9 stock wiring did it at the sensor had headers duals on both check engine light went on. did what i told you no problems since. of course i put in a pipe that is straight threw with 02 bung and installed sensor. word of advice when jerry rigging your wiring do at the sensor so if you mess up, sensor is cheaper than harness!!!!
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