BACKFIRING AT 4K

moman327

Member
First a backstory :

hey guys

So few weeks ago had a wrist pin blow in my mustang so i found a junk yard got an engine swapped it in and now I have 5 codes. I did not put any of my parts on the new engine except the cai and hooked up to the dual exhaust.
So I restored to stock tune.
im getting
p1000( I know it means nothing just from where it hasn't run enough yet)
p1124
p0320
p0505
p1101
I have an 02 and the guy i got the engine from says it is an o2 as well but pat of egr system is different and has a different plug so i used a harness off on the "new" motor. Now it runs fine until 3.5k it hiccups and the runs fine. Also when it is in park it acts like there is a rev limiter at 4k. Now when we first put it in it was hitting that rev limiter around 3.5k so we put the old iac cam sensor crank sensor tps cause it don't ever remembering it doing that before. Buddy said maybe harness is pined different. Any suggestions?
Thanks guys
Bobby


i posted this in the 2011 section by accident still are getting codes if i read it but no cel also will backfire at 4k and stutter if i get on it to pass someone or get on the highway will not go above 4k i d have it with the bama tune again it it seems fine until that 4k mark

thanks
bobby
 

Markstang

Polishing my banhammer
I'm almost positive that there is a rev limiter in park/neutral set to around 4k rpm so that's not something to worry about. Don't mix and match wire harnesses from different motors. If the wiring is different, the sensor is different. Swap the egr sensor and stuff from the old broken engine onto the new engine.

all four of the codes you listed are for the TPS, crank position, IAC, and MAF being unplugged or showing incorrect voltages. It seems likely the engine wiring harnesses are differently pinned. Don't mix older parts with newer wiring harnesses. It's very possible that with voltages going to the wrong pins that you've ruined some of those sensors now.
 

Jesse01V6

Away from V6's for now........
X2^^^^

That PCM doesn't know what the F is going on..... Its expecting certain data from those sensors but the wiring harness you put on it is feeding it different voltages its not expecting to see.

Hope you have your old harness still....
 

fasterthanyou

Active Member
Like they said. Use the wiring harness that came with your car originally. If the harness doesn't plug into a sensor because of a different shaped plug, then swap the sensor from your old motor onto the new motor. Hopefully nothing got toasted from a wrong harness being used
 

moman327

Member
hey guys sorry to resurrect this but i have lost all hope. so the buddy i had do the swap for me is mia got fired from where we work moved from his house that he was at when we did the swap and phone is shut off. had left the old engine there had no use for it and now it is gone. i do still have the original harness. so the sel went off a week after the last post. so out of sight out of mind sstill had the back firing at 4000 rpm but due to trying to finish a house before i got married and getting married in november haven't had time to screw with this. when it got real cold it would die on idle when i start it in the am but start right back up and warm up. i then got the cel light again and its was tps out of range and iac out of range. light went away in a day before i went to my stoarge unit to see if i had these still off the old motor( i dont) so again out of sight out of mind. kicked back on again yesterday i lent my reader to a buddy but im sure that will be what it is so memorial day i am looking to do (again) put the heads /cam/ headers on ad figured it would be a good time to do it so trying to find pics online at what it is supposed to be I see my current config with the dpfe sensor ( doing research was what was different ) for 02 v6and now i am scratching my head as wtf the "new engine has a pedestal style where it comes into bottom and it is flat where the one that was on there was shaped more like a breifcase if memory serves me correctly whis i have found but i only seen that style on one 99 ( google images) i need to figure this out because next month I am a year over due on inspection and need to get this figured out can i do egr delte from my tuner and still get through emissions some how?i hear about this dont know how true it is would either of these codes affect the backfiring at 4k or this sensor
 

Phil II

Cone Destroyer
Can you re post your issues just a little better organized?

Do you experience misfiring at only 4000 rpm? Is the idle rough? At WOT does the engine deliver relatively smooth power?
 

moman327

Member
ok original egr set up is gone
idle is fine other than a couple really cold days it would stall and within 30 seconds but fire right back np
If I was to stomp it it takes off great until that 4k point where it hits a wall and immediately drops to 3k-3.5(fluctuates) and sputters until I let of gas and it catches itself
looking at pics the car has the right dpfe sensor now but didn't before this was why i had to swap the harness to the one that came with the engine in referenced in the op. The one that was on the car when I bought it was the style a picture of one i found on a 99 that was the only different sensor
 

Phil II

Cone Destroyer
Will your motor turn no more than 4k rpm? Does it make a difference if you're in neutral? Auto or manual?
 

moman327

Member
auto
it is almost like there is a rev limiter at 4k it would go if it did not backfire and fall on its face

I have not tried it in neutral
 

moman327

Member
ok so i got my tuner back today read all of the codes that were in the original post again
1101
0320
1124
0505
also threw it in neutral on my way home last night on the side of the road reved it up it hits 4k smooth pulling good and bounces down to 3500 and revs back up no back fire Almost like it is a rev limiter but again i looked at my tuner and there is not used
 

moman327

Member
Im going to be getting under the hood next week any way to try to help pinpoint the issue we are going to swap the harness and just not hook up the dpfe sensor for now but how to we track down what could be the issue here I did unplug the iac and the car stalled right away
 

moman327

Member

THIS WAS THE STYLE OF THE ONE THAT WAS ON THERE

THIS IS WHAT IS ON THERE NOW ANYONE ELSE SEE ANYTHING LIKE THE FIRST ON A 2002?
SEE HOW THE PLUGS ARE DIFFERENT HENCE THE HARNESS CHANGE

I DID GET A HOLD THE THE GUY WHO DID THE ORIGINAL SWAP FOR ME HE IS GOING TO CHECK TO SEE IF HE HAS THE ORIGINAL INTAKE FLOATING AROUND WHICH HAD THE EGR SYSTEM ON IT
 

moman327

Member
Update
i did get a new code but it cleared it self before i had a chance to work on it along with the rest of them again this time it was bank 1 lean ( i have a bad exhaust leak on that side as well )

so got to work on it a little last night we data logged it on the way to my a friends house say that 3&4 were misfiring pulled plugs they were shot. thought they were new when the other guy swapped the engine now it is running better but now i get the back fire and miss fire at 42000ish. also cleaned the maf

we had someone else there too did more data logging saw that my pulse width on injectors is close to 200 off from one side to the other on stock tune.

this morning did a quick data log on the engine on the way to work ( just used the sctx3 stand alone not hooked up to a laptop) and notice my spark was advanced to 25.5 is this normal? also what should I data log to help pinpoint the issues I am having
 

moman327

Member
ok guys got another piece of the puzzle. I have now seem to have lost any power. Takes forever to get up to speed no umph out of it at all. Please I did replace the tps but no help on that front. i am doing a fuel filter tommrow night i have a new maf coil pack wires coming too what am i missing where
 

moman327

Member
yes it did. So I figured out the power loss is due to plugged cats on the back firing side. Ordered new cated xpipe from american muscle. now from reading online this would probably would have been cased by the issue of the back firing rather than causing it correct? The old motor ran strong before we put the aftermarket parts on that i thought was a bent valve in the head ticking and it turned out to be a weak wrist pin. but up until it blowing out had no issues with the old motor. tested the compression on all cylinders all were good. Just fyi
 

moman327

Member
So just giving you guys an update since I was planing on putting the (heads cam headers) on over memorial day i did it now since the car went down. Had a lot of gunk in the intakes swapping out to my old one (cleaned up when we did the swap last year). Don't have the upper from the old or would swap that too found a snapped sensor in the back of the cylinder head replacing all the o2s new wires coil pack maf already replaced tps. Going to swap the plug from the "new" harness to the old one for the dpfe sensor and put the original harness back on new pcv valve any thing else you guys can think of before i try to start this thing up i want no issues whats so ever when I am done for a while ( i know famous last words) Oh and the fuel filter as well will be new.
 
Top