97 gt pi engine swap problems

Khenji Harris · Jun 15, 2018

Had the 99-04 automatic engine swapped into my 97 manual gt at a shop and they swapped over bolt one from the 97 like long tubes, pulleys and cold air intake. Also they had to order a new flywheel for it to bolt to the automatic engine. First time driving out the shop the car seemed to be misifring especially at low rpms, but never threw a misfire code. Under full throttle it would spit/stutter and be very hesitant to go. The shop said it would need a tune because of the modifications and it being the pi engine instead of the npi. Bama sent a custom tune so it's on 87 performance however I'm running 93 octane gas. Only have been driving it tuned for a day there was a little improvement in the spitting but it's still hesitant on full throttle. Also threw codes for

Evaporative Emission Control System Vacuum System – Purge Control Valve,

Catalyst System Efficiency Below Threshold,

insufficient switching of oxygen sensor bank 1,

A Heated Exhaust Oxygen (HO2S) sensor indicating lean at the end of a test is trying to correct for an over-rich condition

mogs01gt · Jun 15, 2018

Sounds like the tune is for a 00-04 and not a 97. Unless you didnt hook up those connectors, you shouldnt be getting those odd codes. Or someone forgot to plug in your o2 sensors.

Khenji Harris · Jun 15, 2018

mogs01gt said:
Sounds like the tune is for a 00-04 and not a 97. Unless you didnt hook up those connectors, you shouldnt be getting those odd codes. Or someone forgot to plug in your o2 sensors.

Shop said there was a problem with the o2 cause they aren't far apart enough from each other, like they are both before the cat he said but that's how it was before the swap was done. I was mainly asking what could be causing the misfiring like symptoms under full throttle

wmburns · Jun 15, 2018

ALWAYS post the full DTC's codes. There are 1,000's and they each have have a story to tell.

Please report the status of:

the fuel system used. Did you use the original return based fuel system?
Did you use the original 1997 fuel injectors?
Are there any exhaust leaks? Especially on the right side?

The 1997 PCM will run the PI motor. It will not however run it perfectly without a tune.

Khenji Harris · Jun 15, 2018

wmburns said:
ALWAYS post the full DTC's codes. There are 1,000's and they each have have a story to tell.

Please report the status of:

the fuel system used. Did you use the original return based fuel system?

Did you use the original 1997 fuel injectors?

Are there any exhaust leaks? Especially on the right side?

The 1997 PCM will run the PI motor. It will not however run it perfectly without a tune.

P1443
P0420
P1131
P1151
I'm not 100% sure on all the specifics that were done because it was done at a shop, he did mention that they had to swap the fuel rails or something along those lines

wmburns · Jun 15, 2018

I didn't think that a Non-PI exhaust manifold would bolt up to a PI head. Are you positive there's isn't an exhaust leak?

>>

Electrical:
- Short to VPWR in harness or HO2S
- Water in harness connector
- Open/Shorted HO2S circuit
- Corrosion or poor mating terminals and wiring
- Damaged HO2S
- Damaged PCM
Fuel System:
- Excessive fuel pressure
- Leaking/contaminated fuel injectors
- Leaking fuel pressure regulator
- Low fuel pressure or running out of fuel
- Vapor recovery system
Induction System:
- Air leaks after the MAF
- Vacuum Leaks
- PCV system
- Improperly seated engine oil dipstick
EGR System:
- Leaking gasket
- Stuck EGR valve
- Leaking diaphragm or EVR
Base Engine:
- Oil overfill
- Cam timing
- Cylinder compression
- Exhaust leaks before or near the HO2S(s)

Khenji Harris · Jun 16, 2018

wmburns said:
I didn't think that a Non-PI exhaust manifold would bolt up to a PI head. Are you positive there's isn't an exhaust leak?

>>

Electrical:

Short to VPWR in harness or HO2S

Water in harness connector

Open/Shorted HO2S circuit

Corrosion or poor mating terminals and wiring

Damaged HO2S

Damaged PCM

Fuel System:

Excessive fuel pressure

Leaking/contaminated fuel injectors

Leaking fuel pressure regulator

Low fuel pressure or running out of fuel

Vapor recovery system

Induction System:

Air leaks after the MAF

Vacuum Leaks

PCV system

Improperly seated engine oil dipstick

EGR System:

Leaking gasket

Stuck EGR valve

Leaking diaphragm or EVR

Base Engine:

Oil overfill

Cam timing

Cylinder compression

Exhaust leaks before or near the HO2S(s)

Like I said I'm not 100% sure so there definitely could be an exhaust leak, but could all those things you listed above be the cause of the misfiring symptoms under full throttle?

wmburns · Jun 16, 2018

The DTC codes are trying to tell you that the PCM "thinks" it has lost control of the air to fuel mixture. The O2 feed back loop is broken and the PCM does not know how to correct it.

And yes any one (or more) of the items listed "could cause" the DTC to be thrown. The trick is to figure out which one.

IMO it's also naive to expect the motor to make smooth WOT power under the circumstances. In fact it might be down right dangerous to force the motor to make maximum power with outstanding DTC codes.

In general this trouble shooting should start with the misfire at part throttle. Why? Because the part throttle is where the lack of tune will have the least effect (the non-PI PCM should be able to run a PI motor assuming everything else works). Are you positive that the spark plugs wires have been correctly routed and that all factory stand offs and looms used?

Other notes. It is well known that long tube headers and O2 sensors don't always get along. Add to the mix an exhaust leak and this will make a bad situation worse.

How to trouble shoot this problem? You need data. Having a graphing ODB2 scanner might make real short work of this problem. Otherwise it's "load up the parts cannon" and start guessing.

Here's some information on an affordable Windows based ODB2 scanner with graphing capabilities.

ForScan ODB2 scanner w ELM327 USB

https://www.stangnet.com/mustang-forums/resources/forscan-odb2-scanner-w-elm327-usb.57/

Khenji Harris · Jun 16, 2018

wmburns said:
The DTC codes are trying to tell you that the PCM "thinks" it has lost control of the air to fuel mixture. The O2 feed back loop is broken and the PCM does not know how to correct it.

And yes any one (or more) of the items listed "could cause" the DTC to be thrown. The trick is to figure out which one.

IMO it's also naive to expect the motor to make smooth WOT power under the circumstances. In fact it might be down right dangerous to force the motor to make maximum power with outstanding DTC codes.

In general this trouble shooting should start with the misfire at part throttle. Why? Because the part throttle is where the lack of tune will have the least effect (the non-PI PCM should be able to run a PI motor assuming everything else works). Are you positive that the spark plugs wires have been correctly routed and that all factory stand offs and looms used?

Other notes. It is well known that long tube headers and O2 sensors don't always get along. Add to the mix an exhaust leak and this will make a bad situation worse.

How to trouble shoot this problem? You need data. Having a graphing ODB2 scanner might make real short work of this problem. Otherwise it's "load up the parts cannon" and start guessing.

Here's some information on an affordable Windows based ODB2 scanner with graphing capabilities.

ForScan ODB2 scanner w ELM327 USB

https://www.stangnet.com/mustang-forums/resources/forscan-odb2-scanner-w-elm327-usb.57/

Wow okay thanks man that info has been helpful, I guess I'm gonna take it to an exhaust shop to take a look at the o2 sensors and the cats and any exhaust leaks and start there

mogs01gt · Jun 18, 2018

Khenji Harris said:
Wow okay thanks man that info has been helpful, I guess I'm gonna take it to an exhaust shop to take a look at the o2 sensors and the cats and any exhaust leaks and start there

Like burns said, non-pi manifolds may not be the same size on the primaries.

What color are the injectors.

Khenji Harris · Jun 22, 2018

mogs01gt said:
Like burns said, non-pi manifolds may not be the same size on the primaries.

What color are the injectors.

Think they are orange, always get them confused with the spark plugs

97 gt pi engine swap problems

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