I have a 03 suburban that had the 5.3 in it. The motor blew and i had a 4.8 at the shop that i put in it. now the 5.3 was set up for flex fuel and i didnt care to have it so i kept the 4.8 as it was without flex fuel. after driving for couple months im starting to get rough idle, engine stalling while driving and wont start again for awhile, i replaced crankshaft position sensor but it didnt help. hooked my scanner to it and getting a P0178 code, which now i realize can cause all my symptoms. is the only way to fix my problem at this point is to tune it out? or is there another way to bypass it? or is this even my problem? lol maybe crankshaft position sensor?
p0178 code after engine swap
- Thread starter brads0813
- Start date
Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.
Are the connections to the fuel composition sensor good, and have you been running NON-E85 (only gas)? Did you make any changes to the PCM or have anything tuned?
Assuming that you've been running only gas (E10, not E85) your scanner should be able to verify that the alcohol content is 10% or below. If it's higher, reset it with the scanner. And verify the connections to the fuel composition sensor because that's what the code points to, a circuit problem.
And anytime a crank position sensor is changed, a CASE relearn is recommended. Not always necessary, or required, but not doing it can lead to random misfires.
Assuming that you've been running only gas (E10, not E85) your scanner should be able to verify that the alcohol content is 10% or below. If it's higher, reset it with the scanner. And verify the connections to the fuel composition sensor because that's what the code points to, a circuit problem.
And anytime a crank position sensor is changed, a CASE relearn is recommended. Not always necessary, or required, but not doing it can lead to random misfires.
I have not ran e85 in it at all. When I switched engines I used the pcm I had. Drove it perfectly fine for about 4 months and then it started to get rough idle every once in awhile and could smell fuel like it's running rich. Then one night it just shut off on us while driving. Like you just turned the key off. No check engine light or anything. The p0178 was a stored code along with another evap code. Changed crankshaft position sensors ( no relearn) but it ran for few minutes and then again like you turned key off it shut off. No sputtering or anything
If it'll run, look a the fuel trims. High positive fuel trims at idle indicate over-fueling. That can be caused by the calculated alcohol content being incorrect, among other things. Check that alcohol content with a good scanner if only to rule it out.
I have a snap on scanner im not sure if it reads alcohol content or not to be honest. Need to get an Autel lol...but yea makes sense to me that no other codes are pulling up, just those. No active check engine light on. Battery and alternator have been replaced, I checked all the grounds I believe. Once it does turn off it dont want to restart
Joseph Garcia
Supporting Member
- Joined
- Aug 2, 2018
- Posts
- 7,151
- Reaction score
- 9,584
Welcome to the Forum from NH.
Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.
I hope that you will become a participating member in the Forum's discussions.
Pics of the truck, please.
You are already receiving sage advice from the knowledgeable folks on this Forum.
Lots of knowledgeable folks here who freely share their knowledge, experiences, and perspectives. Knowledge is power.
I hope that you will become a participating member in the Forum's discussions.
Pics of the truck, please.
You are already receiving sage advice from the knowledgeable folks on this Forum.
