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91 vert fixed omp with a good ecu still in limp mode

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Old 04-19-11, 09:55 AM
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91 vert fixed omp with a good ecu still in limp mode

i think the only challege i have left is adjusting the tps sensor. the original tps was bad so i found one off a turbo, and i have another one off of a 91 vert standard. i guess all i really want to know is if the tps is different for an automatic?
Old 04-19-11, 03:31 PM
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*First* Welcome to the forum!

Second: what codes is your ECU throwing? Can't have a discussion unless you tell us the codes.

Let us know, good luck!

-Jack
Old 04-19-11, 03:58 PM
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Welcome! Limp mode is a bitch, an absolute bitch....

Regarding the OMP and the ECU, how are you verifying that either are good?
Old 04-21-11, 01:01 AM
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ok, ok not real sure what codes im getting right now. It should be just code 18, narrow range, and the wide range tps code. I dont know cause im going to put in a new ecu.
I know my ecu is good cause ive opened it up and looked at it, it also came out of another car jut like mine. The original ecu was burned up and one of the chips was cracked. my original ecu is a n353 and the one ive got is an n352, im hoping that it's compatible.
i installed a new omp and i can clearly see it pushing oil so im guessing its good
Old 04-21-11, 07:11 PM
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alot of time when in limp mode ...it will nock out your
tps ecu omp all at once
Old 04-21-11, 10:54 PM
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Have you reset the ECU? Take the ground off the battery to clear the codes.
Old 04-22-11, 09:33 AM
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I thought my ECU was good initially until after taking a second look with a magnifying glass noticed a hairline crack (from burning out) running right up the Toshiba component that supports the OMP. The failure of this part from a bad OMP isn't as obvious as it first seems as I've come to learn.
Old 04-22-11, 09:51 PM
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Originally Posted by bac22
I thought my ECU was good initially until after taking a second look with a magnifying glass noticed a hairline crack (from burning out) running right up the Toshiba component that supports the OMP. The failure of this part from a bad OMP isn't as obvious as it first seems as I've come to learn.

Circuit boards don't always show any visible sign that anything is wrong. Chips go bad inside, all the time. Over heat, too much voltage, ect . IC chips are tough but they do fail - inside.
Old 04-23-11, 09:23 AM
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So you've only replaced the ECU?

You need to replace both the OMP and the ECU. If the ecu was bad, it was because the OMP killed it, just like it will kill your new ECU.
Replace the OMP with a good working one, and then replace the ECU with a good working one.

If you don't want to do that, block off the OMP, OMP injectors, and get a piggyback(Rtek) or Stabndalone (Megasquirt, microtech, haltech etc.) that you don't need to run an OMP with and premix.

When this happened to me, I bought a BRAND NEW OMP($1500) and got a good used ECU. I don't suggest that route. I should have just premixed and gotten a megasquirt, but I had different plans for the car at the time.
Old 04-23-11, 09:41 AM
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He's got another OMP, he's just not sure if the ECU is whacked out or not.

Regardless, it would behoove you to take molotovman's advice and get some type of system on there, such as an rtek, to allow you to get rid of the OMP and just premix before the same thing happens again.
Old 04-23-11, 10:18 AM
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Originally Posted by texFCturboII
He's got another OMP, he's just not sure if the ECU is whacked out or not.
He never changed the OMP, he's only said he changed the ECU.
Old 04-23-11, 01:54 PM
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open the ecu before installing and see if the 2 resistors are burnt
Old 04-23-11, 02:28 PM
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Originally Posted by will817
i installed a new omp and i can clearly see it pushing oil so im guessing its good
Old 04-24-11, 12:35 PM
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No no I have replaced the omp. I'm pumping oil pretty good. I just need to know if the tps is the same from a standard cause mine is an automatic. I've got 3 tps sensors one off of a turbo, a standard and my old one. I've made a test light and tried to tune it myself but with no luck. I wanna drive this car so bad, I hate limp mode
Old 04-24-11, 06:57 PM
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Originally Posted by will817
No no I have replaced the omp. I'm pumping oil pretty good. I just need to know if the tps is the same from a standard cause mine is an automatic. I've got 3 tps sensors one off of a turbo, a standard and my old one. I've made a test light and tried to tune it myself but with no luck. I wanna drive this car so bad, I hate limp mode
Yeah I failed to read every post Sorry Tex.

See if you can borrow a Digital Multimeter from someone you know. Any Electrician or HVAC person should have one.
Old 04-24-11, 08:24 PM
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Originally Posted by will817
I wanna drive this car so bad, I hate limp mode
Hey Will, you really need to pull the codes so you know what is causing the limp mode. You are really just guessing at the cause.

To restate, if you are in limp mode, there will be a code or several codes. Pull them, then you will know what is causing the limp mode.

Then you have a good place to start.

http://www.1300cc.com/howto/how2/codes.html

Good Luck!

And one more thing: Just because the OMP is pumping oil, that does not mean the OMP is good! The OMP will still pump oil if it has 'failed'. It will pump at what ever volume it was pumping at when the stepper motor stopped working. The electronically controlled stepper motor part only varies the rate of pumping. It does not pump the oil electronically. The pump is an electronically controlled variable rate mechanical pump.
Old 04-24-11, 09:22 PM
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Im going to get the codes off of it and post them soon
i have a snap on mt2500 scanner so i can scan it pretty good
Old 04-24-11, 09:26 PM
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Originally Posted by will817
Im going to get the codes off of it and post them soon
i have a snap on mt2500 scanner so i can scan it pretty good
You don't need that. I don't even think it will work, but I really don't know...

The codes are read by the check engine light. All you need is this link. Instructions are pretty simple to follow.

http://www.1300cc.com/howto/how2/codes.html
Old 04-24-11, 09:51 PM
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yeah my scanner works and ive got the mazda adaptor
ive used it before much easier than doing it manually
Old 04-25-11, 05:54 AM
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Originally Posted by arad99
Circuit boards don't always show any visible sign that anything is wrong. Chips go bad inside, all the time. Over heat, too much voltage, ect . IC chips are tough but they do fail - inside.
Yes...I'm an EE in digital electronics and realize that...my point is that sometimes a visual inspection doesn't show a bad part even though it is bad. Initially when I started troubleshooting my OMP failure the common theme in threads is that burnt out parts in the ECM was a common indication.

That maybe so, but in my case a quick visual of my ECM showed no such damage even though the circuitry for the OMP was bad.
Old 04-25-11, 11:10 AM
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ok so ive visually inspected my ecm, it looked ok. is there any other way of testing it ?
Old 04-25-11, 11:32 AM
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Originally Posted by will817
ok so ive visually inspected my ecm, it looked ok. is there any other way of testing it ?
You can always read each pin at the ECU and compare to spec as found in the factory manual. Also, how are you tuning or setting your TPS?
Old 04-25-11, 11:40 AM
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i made a led light and hook it up to the 3 prong dill by the air box and adjust the tps but i dont know if thats working good or my tps is messed up
Old 04-25-11, 12:12 PM
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Originally Posted by will817
i made a led light and hook it up to the 3 prong dill by the air box and adjust the tps but i dont know if thats working good or my tps is messed up
You can set the TPS to one volt which would be measured from the Green/Red wire of the TPS plug/connector. Car should be fully warmed up (20 minute drive usually does the trick) and w/key to on, adjust the TPS adjustment screw if out of spec (1 volt).
Old 04-25-11, 12:48 PM
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ok ive got codes 18 27 and 12
i hope that ecm didnt blast the omp


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