back fire from intake

[mcjr450]

backfire from intake

I have a 93 ford ranger.. I pickex this truck up about 6 months ago.. when I first got it I changed the oil spark plugs air filter and timing belt. It ran awsome for the first 3 months the all of a sudden it died on me.. so then ireplaced the fuel filter fuel pump and radiator, I changed the radiator cuz of rust. The truck ran ok for a coup, e more weeks after that but then it started to hesitate and backfire through the intake. I ran a comp on it and it through theses codes.. o2 temp sensor idle air control valve and maf sensor.. I replaced all of those brand new. The weird thing is thoughin the last 3 months it would run fine for a week then be down for two.. it did this off and on for the last 3 months. I just put the iacv in today since all those sensors are really expensive so I did it a lil at a time. Now that i just replaces I iacv it still backfires through the intake.. the truck wont even idle right and takes forever for it to even start and when it dose I have to pump the throttle to get it to berley idle. At this point I have no idea what it could be or what could cause this. I cant even run a test on it cuz it wont stay ildeling l8ng enough to throw any codes. So what my question is where do I go from here, what kind of things could cause it to backfire from the intake? I am really confident that the timing is set right since I did that over 6 months ago and it ran perfect for about 3 months befor it showed and hesitation and just died on me. And what really has me confused is why would it just decide to run good for a week or two and decide to just quit on me when it wants to.. any kind of feed back would be greatly appriciated! If their is anything else you would need to know just ask and ill try to answer it to the best of my knowlage. Im a pretty decent mechanic not the best but I know my way around and engine.

 

[Mark_88]

Welcome to TRS~!

First thing that comes to mind is timing...second thing is fuel mixture...too rich or too lean...probably too lean from an air leak somewhere like the intake manifold or a vacuum line that is off...

The idle problems also indicate both of these as possible causes...could be other things but that should keep you busy for a few hours checking the timing and looking for air leaks...

But, then again, it could be a sensor out of spec...and you may need to have someone check the codes for you while you keep it running...

 

[stateranger]

I would check to see if the egr valve is sticking. That will cause rough idle and backfiring through the intake.

 

[mcjr450]

Ok how would I double check the timing without the plastic cover? Mine brike off when I replaced the timing belt.. I marked it back when I replaced it but the mark is faded out now.. And im not too sure how to check if the egr is sticking.. thank both of you guys for your replys.. im gonna go check the vaccum lines right now to start with

 

[mcjr450]

Ok I found 1 vacuum line missing.. from throttle body to carbon canaster.. its the dotted line on the vacuum diagram.. how important in that one? I took a look at the egr..mdosent seem to stick but again im not entirerly sure how to check it

 

[stateranger]

Its important because that is a large vacuum leak if its not attached to the intake.easy way to check the egr to hook it directly to vacuum source at idle or just suck on a piece of vacuum line attached to the egr while at idle, the engine will run run very rough or die. He ment check to make sure the marks on the cam gear, oil pump gear, and crank gear are lined up properly.

 

[mcjr450]

Yea I was just talking to a friend of mine that works parts at ford.. he also told me its important to have that vacuum line on there.. it definatly makes sense to me.. letting too much air into the throttle body would lean out the fuel mixture too much.. hes gonna pick up the line for me tomarrow.. I do remember a while ago I was working on the truck and the line was so brittle it just fell right off.. idont know why but I just didnt think anything of it.. im almost positive thats whats causing this.. well atleast I hope so.. lol ill let you guys know how it gose after I put that line on.. if it dosent turn out to be that ill do the erg next, its just tring to get the truck to idle long enough to check it

 

[mcjr450]

I just replaced that vacuum line.. the truck started right up abd idled for the first time in 3 months.. I took it for a test drive and at first it didnt want to run till the teuck warmed up a lil bit then it dirves just normal now.. still a lil bit of hesitation but itseems the more I drive it the better the truck runs.. might be some carbon build up I just need to blow out.. Im gonna run a comp on it right now to see if it throws any codes.. im really happy right now with the results of just replacing that line.. I thank you again with you suggestions and atleast now I got all those new parts on my truck.. lol

 

[mcjr450]

K here are the codes It threw.. 172 o2 sensor lean and 543 fuel pump battery to powertrain.. both of those are brand new and now I dont see any other vacuum leakes.. the check engine light flashes on and of as im driving andthe truck hesitates.. itll drive fine for a lil bit and then itll just loss all power and I cant get it up to speed.. im also getting a strong fuel smell.. with the timing I dont have the tim7ng belt cover which had the mork for the oil pump gear I belive.. the cam gear and crank gear are in the right spot I just cant find a mark for the oil pump gear

 

[stateranger]

Check all of the grounds.also when was the last time the mass air flow sensor was cleaned and fuel filter changed.

 

[mcjr450]

Both the mass air flow and fuel filter are new.. less than a couple months, trucks been siitin more than on the rd for most of that time.. ill def check the grounds though

 

[zekew64]

I'd check your fuel pressure regulator. It also works off of vacuum; it works off of the same vacuum circuit that the EGR does. However, there should be a pair (one red, the other green) of lines that goes across the firewall to a vacuum switch, then back to the EGR and the intake manifold vacuum tree. I'm thinking that the fuel pressure regulator is failing.

As for the timing, all you have to do is locate the crank pulley at 12:00 and the cam pulley at 5:00. After you do so, rotate the cam pulley one tooth forward to get the proper 10 degrees BTDC. The auxillary shaft (oil pump pulley) doesn't matter.

Lastly, I'd replace your fuel pump, as the Haynes Manual I have says that the 543 code you mentioned is a fuel pump secondary circuit failure. I think that what this means is a circuit that protects the pump so that it keeps fuel flow in line with engine RPM. Again, replace the fuel pump.

 

[mcjr450]

0the fuel pump is brand new.. I just replaced it about 5 months ago and for the majority of that tie the trucks been sitting.. just running occasionally when it wants to.. ill definitely check fuel pressure regulator and the timing.. thanks for helping me out with that.. thats what I was looking for with the timing