heavy backfire / afterfire at 3000 rpm

[malcantry]

hello hello

so I posted about this a few months ago, but I have done a few things since, hopefully I can get a little input from you guys

from the beginning:

I had just finished my build last december and was running around in my car for 2-3 months with very few problems, mainly tuning.. I then managed to strip out 1st, 5th and reverse in the tranny so I parked it in my driveway until i could get a new trans to throw in it.. The car sat for about 4-5 months till mid summer and I got a new trans and put it in.. however, when i pulled the car into the garage from driveway, I found that my relocated battery in trunk had actually tipped over before I parked it and it was seeming out battery acid the whole time it was sitting there..

After doing the transmission and getting everything back together, I am able to turn it on and run it, new battery of course.. (sounds smooth as hell at idle and past.. to like 2500rpm)

I then tried running it on street and i couldnt get it past 3000RPM without it just firing like crazy..

SINCE THEN;

I have cut wire in trunk to try and put terminal connector back on good wire.. The wire INSIDE the insulation has signs of oxidation and corrosion.. so I decided to F the idea of the battery in trunk and place it back in engine bay, as close to the electrics as possible and getting rid of the corroded wire from trunk to eng-bay..

I still had same problem.. so i removed the alternator and took it to autozone for testing.. what do you know.. tested like s***. new alternator. (my car has been draining electricity and killing batteries for a year now, I think it was alternator whole time..)

anyways.. Now i have a new alternator, new battery.. I thought to myself, maybe i need to put good fuel in?? The car has been sitting for 6-8 months with no run time so I figured the fuel could be the problem...

since then;

I have been able to test it on the street and I am now able to enter 1-2 lb of boost and it is still backfiring a little.. I definately cant give it heavy load.. I should be able to hit 10psi no problem.. have before..

I cant seem to wrap my head around it..

bad wideband o2 sensor?

bad fuel? fuel filter? fuel pump is brand new...

bad TPS?

vac leaks?!

IM SCRATCHING MY HEAD SO MUCH ITS STARTING TO BLEED

help please

any suggestions/ideas are praised!

thanks

 

[hornsfan10609]

Sounds like the ignition system, have you checked the plugs? Does the car have fresh gas?

 

[malcantry]

checked plugs, they all look uniform in burn/markings and no abnormalities.. I DID however see some of the same calcifying/oxidation inside the plug holes when I took the plug wires out.. VERY minimal but it was still scary to see.. think I need new ignition coils or wires??

just put in fresh gas.. had about 1/4 tank (old) and i filled er all the way up, 93 octane

I took my car to auto-zone to have the code read, (CEL on), and he couldn't even get it to show on the computer-- ANYTHING.. like it wouldn't even connect? suggestions??

I'm going to try a different MAP tonight.. see if that helps.. I also have a little bit of a melted connector on my wide-band, so I'll make sure to rewire that as well..

any more ideas?!@!@$#!%$!@

thanks horns ;P

 

[hornsfan10609]

Fresh gas is the first thing for sure, I would suspect the ignition setup if it's misfiring. If the OBD port is dead it's most likely a blown fuse

 

[malcantry]

do you happen to know where the fuse is for OBD? is it in-line? i cant seem to find it.. I did however find a blown fuse to.... fog L? (don't even have fog lights)

I re-spliced the wide band o2 sensor wiring since it was all melted.. but I never had any real funny readings from it.. always between 10-11ish while I'm trying to get under load..

I've put in new alternator.. new battery.. put battery back in engine bay.. rechecked all plugs on coils.. pulled spark plugs and put em back in a few times.. worked on ignition wires and their push-ons.. changed fuel map..

Sooo... I'm really frustrated right now..

What to try next? New coil packs?

 

[malcantry]

Ok,

Just got back from the junk yard.. I picked up MULTIPLE sensors (MAP is one of them) and I'm going to start replacing these little buggers as soon as I get home..

I was actually able to find a MAF sensor as well.. super lucky find because they're normally all gone real fast. I didn't get it at the moment but the guy said to "go hide it" and I can come back for it any time if I so decide that may be the culprit to my problems. But for 45$, the MAF is a steal...

That's one of the last things on my list of possibilities, but what do you guys think? Replace MAF??

Unfortunately, I wasn't able to find any coil packs / ignition wires that were good.. I ALREADY have upgraded Nology HotWires,... what are the chances of them going bad??? Less then 2000 miles on em.. No way right? Idk..

 

[malcantry]

Riiight...

So, I replaced multiple sensors.. I was not 100% completely sure about the MAP sensor and the one located right next to it.. I picked several from the junk yard and I replaced one of the two in the passenger corner at the strut bar, but the second one I was looking to replace didn't match with the numbers of the one I got from the yard. So it's in limbo.. Not completely sure if the one I replaced is the MAP sensor or the one I didn't replace.. Which is correct #'s for the MAP sensor???

I replaced a total of 3 sensors, and I made a few jumper wires to help ground a few things out.. went for a drive.

ALSO;; I had a full tank of gas and added a full bottle of fuel and injector cleaner, but since I had a full tank it's quite diluted. (Instructions said to add bottle with fuel tank under 1/4, drive a few miles then top off with gas. This allows high concentrate to run through engine for a short time then a diluted amount to run through for remainder of tank after filled up.. I was not wanting to run the car for 200+ miles to get down to 1/4 tank so I put the juice in at full tank, so high dilution..)

I also said 'f it' and got a new set of spark plugs.. some nice iridium's :X

NOW.. with the drive..

I definitely got past the 2900-3000 RPM mark I couldn't for the life of me get past before.. but it's still happening, right at around 3300-3400 RPM..

Should I post a fuel map recording? I'm running fairly rich, even at low RPM, but seems to peg nicely around mid 10's when im getting closer to -1 to +1 PSI of boost @ ~3000 RPM..

help?

thanks..

 

[malcantry]

heeeellllppppp

blah :/

Every time I find something I think "YESS! NOW ITLL WORK AFTER I FIX THIS ONE THING!"

never


I decided to take out my MAF and have a look.. What do I find? Water/Glycol in my inter-cooler piping! wow.. now, it really isn't very much, residue really, but it was a big AHA moment thinking the MAF was just dirty and having problems functioning.. Now, the source of the glycol being in the pipes has been found and fixed.. (coolant reservoir overflow tube was dripping close to intake filter) All the pipes have been cleaned and I got a MAF from the junk yard. I even went and bought some MAF cleaner from the auto parts store and cleaned both the original and the one I just picked up before installing..

I could have sworn this was going to solve my problem.. But no, of course not..

Here's whats been done so far..

New alternator
New spark plugs
New grounding wires to any electrical solenoid or questionable piece that may need it
New battery
New battery connections
Removed old corroded battery wire
New MAP sensor
New MAF sensor (used from j-yard but cleaned!)
Checked fuel line output pressure (strong!) pumped 5gal in ~3-4 min
Added injector cleaner to gas
Checked fuel filter
Checked all fuses / relays
Removed all charge-piping and cleaned and re-installed
Checked all boots/connections
Checked all vacuum lines, builds boost to 1-2 psi

I'm still getting a CEL, haven't tried reading codes again, will do that tonight..
The only thing that hasn't been changed out are the coil packs.. I have new Nology HotWires, less then 3k miles.. Everything should be working properly.. I've got a small exhaust leak on ex manifold but its been there and car was running fine before..
Besides that.. my only other suspect at this point is the o2 sensors.. my wide-band seems to be reading just fine, but I haven't pulled the other sensors yet.

Need some direction!! Please, any input is helpful!!!!!!!!!!!!

 

[hornsfan10609]

Did you suck up any air into the intake, during a rainstorm or something? That happened to my car and water kept hitting the MAF, it was like fuel cut any time you floored it. You are making it more difficult for yourself by replacing sensors at random. Keep it simple, replace the coils and see what happens, try your stock plug wires. Are the plugs gapped properly?

First thing is to get the OBD port to read so you know what CELs you have, could even be a bad ECU if it can't connect.

 

[malcantry]

Spark plugs all .032-.033, brand new.

Unfortunately I can't find my original plug wires

I had sucked up water a LOOONNNGGGG time ago, actually the day I bought the car. I was driving it home and tried like hell to not get off the freeway.. When I exited to get gas, I hit some high water.. EVERYTHING has been redone since then and it was working fine.. That was 4+ years ago..

Just bought a new set of coils, not in yet

I'll take the car to autozone tonight and have em try to re-read the codes and keep you posted..

Thanks for your 0.02$ Horns <3

 

[malcantry]

If I go sensor replace crazy, then if my problems is solved.. then I can just reverse install the original sensors to see which failed me

Lol, I know it's a little backwards, but it keeps me from test running it after EVERY sensor change which could possibly do more damage then good whilst running..? I'm trying to be a little systematic.. ish..

Fuel, check
Air, check
Battery power issues, check

Now ignition / ECU / incoming signals :x

 

[hornsfan10609]

ECU should be the first thing, it tells you where the problem is!

 

[malcantry]

edfhngiujaehnfhae

I replaced my ignition coils.. They were basically the only thing that hasn't been replaced on the car in the last 2 years..

same problem.. what do you know..

I checked EVERY fuse.. EVERY ONE. Found interior dome lights fuse has blown..

FUTURE REFERENCE GUYS!!! IF OBD PORT IS OUT, CHANGE 10A FUSE AT DRIVERS FOOT PANNEL LABELED:: ROOM 10A

straight back to Autozone..

2 codes

1 = duh,P2009, VTCS solenoid. eh

2 = ahh, P0340; Camshaft sensor. Circuit Malfunction
Probable cause
aa1. Open or short circuit condition
aa2. Poor electrical connection
aa3. Engine mechanical condition
aa4. Faulty Cam sensor

dfghjlkasjhklasjhfa!!! At least I have a direction and I'm not just grabbing stuff from the junk yard willie-nilly now :x

I'll let you know after I've check the circuit, but there's a few other threads concerning this and they have had their timing off..

Hope it's not timing being off by a tic, don't see how it could be though.. I did it perfectly! No collisions, only thing was throwing out the transmission..

 

[hornsfan10609]

If the timing belt tensioner failed it's possible for the belt to have slipped. Glad you were able to get the codes read, now you aren't having to take shots in the dark.

 

[malcantry]

no kidding :X !!! Still haven't gotten anywhere yet, maybe tomorrow

 

[malcantry]

So, I've taken off the valve cover just to have a peek-ski.. Everything looks great! It's been about 4-5k miles since the build and everything still clean and looks to be where it should. All cam bolts still nice and secure.. Timing marks are right on.. everything turns and seems to be solid mechanically.. Can even hear the compression as I turn motor by hand.

Back to the cam sensor and wiring..

I found online here that the cam sensor should read a resistance of 2.1 or 2.2 thousand ohms.. So I pulled the mofo out and its reading 1.09-1.12

I suspected this to be my problem of course, so I went to the junk yard, but brought my trusty multimeter this time.. I tested 3 protege's, ALL OF THEM had the same resistance readings, and NO WAY are they all bad. I didn't even suspect mine to be bad.. So now.. It HAS to be electrical.. I've got my EE buddy coming over tomorrow.. maybe he can find fault where I can't..

Any other ideas guys??

 

[malcantry]

question: does the MSP fire a higher voltage-pulse through the spark plugs at higher rpm or whilst under boost? or is it constant throughout the powerband?