2G P1105 ECU replacement

[Neeland84]

Ok I’ve done quite a bit of searching but what I need is probably more an opinion or advice than anything.

Back story: just bought a pristine example of a 97 Spyder GST with 130k miles and bone stock. 10 mins after I buy it, pops a CEL for P1105. *It’s great to be back in the DSM world*. Guy that I bought it from meets me and swaps his FPS of his other Spyder in the parking lot to get me home 200 miles with newly acquired money pit. Drive it all the way home no problem but the CEL never goes away. Hot starts are sluggish, idle is a little low, but still runs okish. Checked all the vacuum lines on the FPS as well. So I’m leaning more and more towards something with the ECU. It is almost a 30 year old car so I’m not super upset and plan to do extensive maintenance to the car anyways.

Now what to do about getting another ECU. Like i said, plan to just restore the hell out of the car and have its as a nice weather cruiser. So the most modifications it will see is probably an intake, exhaust, and either an upgraded/new side mount or very less likely a FMIC. More than anything I want to keep it looking nice and have it drive well and reliably.

So all that said, is it worth trying to upgrade to something that’s programmable or just grab a factory ECU from rock auto or flagship one?

I had a couple 420a 2gs when I was younger but this is my first turbo car. I'm learning a lot and want to do things the right way, with adult money, and be able to enjoy the car properly for a long time.

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[pauleyman]

Ok I’ve done quite a bit of searching but what I need is probably more an opinion or advice than anything.

Back story: just bought a pristine example of a 97 gst spyder with 130k miles and bone stock. 10 mins after I buy it, pops a CEL for p1105. *It’s great to be back in the dsm world*. Guy that I bought it from meets me and swaps his FPS of his other spyder in the parking lot to get me home 200 miles with newly acquired money pit. Drive it all the way home no problem but the CEL never goes away. Hot starts are sluggish, idle is a little low, but still runs okish. Checked all the vacuum lines on the FPS as well. So I’m leaning more and more towards something with the ECU. It is almost a 30 year old car so I’m not super upset and plan to do extensive maintenance to the car anyways.

Now what to do about getting another ECU. Like i said, plan to just restore the hell out of the car and have its as a nice weather cruiser. So the most modifications it will see is probably an intake, exhaust, and either an upgraded/new side mount or very less likely a FMIC. More than anything I want to keep it looking nice and have it drive well and reliably.

So all that said, is it worth trying to upgrade to something that’s programmable or just grab a factory ecu from rock auto or flagship one?

I had a couple 420a 2gs when I was younger but this is my first turbo car. Im learning a lot and want to do things the right way, with adult money, and be able to enjoy the car properly for a long time.

Pic for attention

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P1105 is not a fuel pressure solenoid. It's a map sensor.
Dont just go replacing parts. I'd check for a leak first. Boost leak check the car and possibly do a vacuum check. Possible a simple vac leak.

 

[Neeland84]

P1105 is not a fuel pressure solenoid. It's a map sensor.
Dont just go replacing parts. I'd check for a leak first. Boost leak check the car and possibly do a vacuum check. Possible a simple vac leak

Huh that’s new information. Everything I can search on here and all the different threads have said that code was specific to the solenoid along with my scanner. Reading thru the other threads it was said that the vacuum wouldn’t throw that code. Only the solenoid being bad or getting a bad signal from the ecu. I checked all the vacuum lines coming off of them. They were all good but one wasn’t quite as tight around the nipple as the others. Put a small clamp on it and the code remained. Cleared the code out with my scanner this morning and drove it some. So far the code hasn’t come back.

However, if I was looking to replace the ecu as part of my major maintenance plan and replacing most everything I can on this car. My question from above still remains. Is it worth it to just grab a replacement factory Ecu from somewhere like rockauto or flaship given my plans for the car. Or should I just buy once cry once with something with more programmability. If so, what would be a good source for an aftermarket Ecu? Most of the ones I have found seem to be discontinued

 

[pauleyman]

Huh that’s new information. Everything I can search on here and all the different threads have said that code was specific to the solenoid along with my scanner. Reading thru the other threads it was said that the vacuum wouldn’t throw that code. Only the solenoid being bad or getting a bad signal from the ecu. I checked all the vacuum lines coming off of them. They were all good but one wasn’t quite as tight around the nipple as the others. Put a small clamp on it and the code remained. Cleared the code out with my scanner this morning and drove it some. So far the code hasn’t come back.

However, if I was looking to replace the ecu as part of my major maintenance plan and replacing most everything I can on this car. My question from above still remains. Is it worth it to just grab a replacement factory Ecu from somewhere like rockauto or flaship given my plans for the car. Or should I just buy once cry once with something with more programmability. If so, what would be a good source for an aftermarket Ecu? Most of the ones I have found seem to be discontinued

Better to send it and have it repaired. Ecmtuning.com
Alternatively if you're going to replace and want some flexibility there are other options. We need to know your plans with the car. Are you trying to modify or are you here just looking for repair info? We've seen it all.

 

[Neeland84]

Better to send it and have it repaired. Ecmtuning.com
Alternatively if you're going to replace and want some flexibility there are other options. We need to know your plans with the car. Are you trying to modify or are you here just looking for repair info? We've seen it all.

Plans are what I laid out in the first post. Tons of maintenance and then maybe some very mild modifications. Intake, exhaust, either a replacement side mount IC with hard pipe or lesser chance of trying to go FMIC. basically just letting it breath a little better and removing some of the airflow restrictions. No real plans anytime in the future to go heavily into mods. I want a reliable, grest looking weekend drive that sounds good and is “quick” occasionally. No real desire for it to be fast.

 

[pauleyman]

I don't have my books handy. Some other post are suggesting I'm wrong and said p1105 is fuel pressure solenoid as you suggested.
Anybody else wanna chime in?

Thing is FPR shouldn't really cause any major symptoms except maybe a mild start problem but nothing once it's running.

 

[chrysler kid]

I reccomend using www.charm.li to find the error codes in the factory service manual

the fuel pressure solenoid is only active if the ecu sees the 5v power reference isnt being used by the solenoid.

if the solenoid is defective the only symptom will be a hot start idle and starting problem. like if you drove to operating temperature, then shut off the car and 5 minutes later went to start it, it would crank a few times and eventually start then it would have a lumpy idle for a few seconds

congrats on the purchase. post a picture under the hood of the engine bay so we can see what youre working with

 

[Neeland84]

I reccomend using www.charm.li to find the error codes in the factory service manual

the fuel pressure solenoid is only active if the ecu sees the 5v power reference isnt being used by the solenoid.

if the solenoid is defective the only symptom will be a hot start idle and starting problem. like if you drove to operating temperature, then shut off the car and 5 minutes later went to start it, it would crank a few times and eventually start then it would have a lumpy idle for a few seconds

congrats on the purchase. post a picture under the hood of the engine bay so we can see what youre working with

Those symptoms are exactly what I’m dealing with and since the FPS was swapped out with one that was working moments before on another car, I’ve been leaning towards the ecu not sending or receiving properly. Which has gotten me to my question on this post about the best path for an ECU replacement. Pic of the engine bay. Completely bone stock

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[chrysler kid]

it would be unusual that the code would be from the ecu failing. 99.99% of the time the ecu fails I have seen are from the idle air control motor going bad and causing the driver capacitors to fail on the ecu.

for the record when mine failed it failed open and my car had zero problems just the check engine light coming on. my 98 had issues when the sensor wasnt hooked to the vacuum line for the fuel regulator. the ecu would try to command a hard start and then the solenoid not doing its correct thing would cause the hot start issue

the part is hard to find. some times its easier to type in the KT part number stamped on the sensor in ebay, the mitsubishi part number will likely yield only jdm parts which are subject to import tarrifs from customs (the screen shot below is not a current ebay listing just from when I bought mine)


(sorry im trying to upload a screen shot of the part listing but have poor reception. will update with photo around 8pm)

 

[Dsm1996Eclipse]

Well the ECU not receving the signal would be more of a wiring issue between the solenoid and ECU, you could do a couple of tests that aren't to hard, a quick resistance test would be a good way to start, the solenoid should be between 36-44 k/ohms at around 68 degrees. You could also do a quick voltage check at the solenoid connector, by pinning terminal No.1 and ground with the ignition on, would be a good way of checking the integrity of the wiring between the MFI relay and the solenoid. There are other tests that you could do to check the pcm but i would start with those.