Mis Fire and Back Fire
 

I took my car out on Sunday, it was quite hot, got stuck behind a parade when I got past it the motor started to misfire took the car home. Started it up a few hours later everything was fine. Started it tonight, it back fired slight smell like catylictic convertor check engine light came on, rough idle , drove it a mile or two seemed ok, then occasional misfire and rough idle check engine light still on. Injectors, O2 sensor?

Re: Mis Fire and Back Fire
 

Howdy Neighbor!!

First thing to check is the MAP sensor hose.
It's behind the plenum on the drivers side.
A backfire will nearly always cause it to pop off.
Usually the car will run rough and smoke a lot with the MAP sensor hose off.
Check it first before we try to diagnose the misfire.

I'm only an hour or so away on the other side of Sacratomato. I'd be glad to lend a hand if you need it.

Tom
'Crabs

Re: Mis Fire and Back Fire
 

Hello Tom, couldnt find the map sensor hose, what diameter is it? Would appreciate some help, thx for the offer, Im just off of Hwy 12 between Santa Rosa Sebastopol.

Thx Richard

Re: Mis Fire and Back Fire
 

The MAP sensor hose is attached to the bottom of the sensor. It's hard to see it. You will have to remove the whole MAP sensor bracket with the MAP sensor attached to really see it and re-attach it if the hose has come off. Here is a picture:

http://i13.photobucket.com/albums/a2...oprearview.jpg

Re: Mis Fire and Back Fire
 

You can get to the hose by reaching from the passenger side, but its really tight. It probably has years of oil accumulation in it, I know mine did. I would take it off and clean it well before reinstalling it. Not to hijack this thread, but does anyone know where can you buy these replacement hoses?

Jason

Re: Mis Fire and Back Fire
 

remember you can build s new one fpr about 10 a the local parts store . they sell the plastic tubing in pkgs you get a wound up abot a ft long you can by one pkg of ends that will work with both ends for 4.99 .use a hairdryer to bend the tubing .very lightly or you burn it up .i just set the dryer over the end of my workbench turn it on low and behold the tubing will bend . alot of guys also use rubber tubing .i just like using the plastic and ends for a line that spends its life in an oven.:mrgreen:

Re: Mis Fire and Back Fire
 

Thx guys I'll take a look tonight!
Richard

Re: Mis Fire and Back Fire
 

FWIW here is another view. I used these spring clamps. They've never come off since.
But then I'm not convinced this is your car's problem. Yet, it is the place to start as was said.
http://home.comcast.net/%7Escottfab/...s/MVC-217S.JPG

Re: Mis Fire and Back Fire
 

I agree, it does sound like he's got other problems, injectors most likely.
But since it had backfired, the MAP sensor needs to be addressed first.
I figured we'd start with the basics and work from there.

Richard, tell us more about your car, year, mods, mileage, the usual stuff.
If it's a '90 or '91 and still has original injectors, it's more than likely time to replace them.
If they've been replaced, the likely suspects are coils, spark plugs, spark plug wires, O2 sensors and on and on and on.
I'm not available this weekend (Mothers Day and all), but next weekend is open (for now, but gotta check with "She Who Is To Be Obeyed").
After that, my next free weekend doesn't happen until June.

TomC
'Crabs

Re: Mis Fire and Back Fire
 

Like I said "Yet it is the place to start like someone said".

My gut says following a parade got the coils hot enough for failure.
Not based on data, just hunch and description. Hope not for his sake.

Re: Mis Fire and Back Fire
 

My car is a 1992 with 59K miles, in the paperwork I have, which goes back to around 20K miles no injectors have been replaced, so that was my first suspect or the O2 sensor. The car is stock. Tom this weekend is not good either but next Saturday is, I'll check out the map sensor hose now I know what I'm looking for, the pictures are great guys, many thx.
What does a set of injectors cost? And what is involved in the install? If the coil has gone out would it still run rough like Im missing a cylinder or two and then somestimes it would run OK?

Thx Richard, thx for the great info everyone.

Re: Mis Fire and Back Fire
 

I checked the map sensor hose and sure enough it has come off the metal tube. I'm looking at it and its about 3/16" dia semi rigid black plastic tube which I cannot get over the flared end of the metal pipe, am I missing something?

Richard

Re: Mis Fire and Back Fire
 

Checking the picture from Jerrys gaskets on Dynamites post Im missing the rubber hose that connects the rigid plastic tube to the flared metal pipe, must blown off when the motor back fired?

Re: Mis Fire and Back Fire
 

i have to go to san andreas next wed to ck on some property i have there . maybe i could stop by early in the eve and help you ck some stuff out .i have 5 primary inj that are still in great shape .pm me if youd like to see if we can connect.

Re: Mis Fire and Back Fire
 

Take a flashlight and look down behind the engine, it might have hung up on something instead of falling on the ground. If you find it, you might be able to reattach it after cleaning with patience and a pair of needle nose pliers. I learned this firsthand about a year ago.

Re: Mis Fire and Back Fire
 

Just as a fwiw, autozone sells vacuum fittings in blister packs. I would think that any auto parts store has the same stuff. You can make a complete MAP hose using the parts store as a source for the missing nipple.

:cheers:
Tom

Re: Mis Fire and Back Fire
 

Ok, I made up a new map sensor hose refitted it, check engine light is now out. I drove the car for about 20minutes and it drove perfectly, pulled like a locomotive! So I'm confused, is it a sign of an injector or coil going bad, are either one of those intermittent when they are going out? Or could it have been stuck behind the parade (actually it was a demonstation by what looked like illegals against the new Arizona immigaration law, welcome to CA!) while the car was cold, fouled up a plug causing the misfire and I didnt give it a chance to clean itself before I stopped the car?

Thx Richard

Re: Mis Fire and Back Fire
 

Richard:

Just a WAG (wild azzed guess), but...
I'm guessing you simply heat soaked the engine to the point where a coil or a spark plug wire started to leak voltage which would have caused it to run rough.

I have some spare coils and spark plug wires we can try if it happens again.
In the mean time, drive it like you stole it!!

C Ya!

TomC
'Crabs

Re: Mis Fire and Back Fire
 

Okay, another fwiw from the peanut gallery. :o

I noticed mine doing the same thing upon cold start....making a fuss & missing & carrying on....sooo last week I took out my IAC and gently used some Throttle Body cleaner on a paper towel to clean the junk off of the pintel and then used a soaked old costco M/Fiber towel to clean out the passage that the IAC goes in. Much better after that little bit of housekeeping.
:dontknow:

:cheers:
Tom