My dad has a 1997 F-150 that I am looking at buying. It has 192,000 miles on it but looks and, until recently, ran fine. It was running decently 4 weeks ago when he put it in his pole barn for the winter. I decided to look at it and when I started it, it shook and felt like it wanted to die but it didn't. My dad had this problem after letting the truck sit for several weeks last Spring but said that it cleared out after driving it down the highway. I drove it 45 miles down the highway and its better, but its still pretty bad. It evens out while under moderate throttle but misses again under heavy throttle and idle. Running at a constant speed causes varied results with RPMs over 2000 seeming to be alright.

I stopped at AutoZone to borrow the scanner and even though the check engine light wasn't on, it posted codes for "multiple misfires" and listed 3 cylinders, then a code for "major vacuum leak" and then a code for the EGR. I don't hear any vacuum leaks at all, is the EGR associated with vacuum?

 

It could be any number of things but most likely is varnish in the injectors. Run some injector cleaner through the tank. Good chance it'll help. So many people on this forum like SeaFoam I feel left out. I've run GM top engine cleaner through several vehicles but worried and changed the oil each time.

 

Thank you. I added injector cleaner, but noticed just before that the exhaust had a VERY strong gas smell to it. Strong enough so that my house smelled at the opposite end within minutes of me backing into the garage and shutting it off.

Any thoughts on coils going out? What would cause multiple coils to go out at one time?

Also, would a loose coil be an issue? I've neverpulled one of these off, but I was checking to see if I could get my hand back to the passenger side, rear plug and when I pushed on the coil, it was loose.

For kicks, I put a new EGR valve on it and that made no change in spite of the code for it being thrown.

 

Let me know. If it hadn't fixed itself before, a MAP sensor with a ruptured diaphram leaking gas into the manifold. But that wouldn't have fixed itself. For that much gas smell, look over the truck thoroughly for external gas leaks.

Let us know.

 

What size engine?

If it's a 4.6L, then I'd bet the plug wires need changing. Mine did the same thing after sitting for a couple of weeks, and I changed out the plugs first (helped some) and finally had to change the wires. Runs like a champ now.

If it's a 5.4L, I believe it has direct ignition where there is an individual coil over each spark plug, with a rubber boot extending down and over the plug. These boots do deteriorate over time, and will cause a misfire - luckily, these boots cost less than a set of plug wires for the 4.6L (a little, anyway) but they are a pain in the backside to change out.

Good Luck!

Jamie D.

P.S. - As for the EGR code, you didn't list whether it was insufficient or excessive. If it's insufficient, you probably need to change the DPFE (do a search on it here) and clean out the EGR ports - the 4.6L is notorious for having blocked ports.

 

The engine is a 5.4 and the EGR code was "insufficient" if I remember right.

The gas smell is definately coming from the exhaust. I scraped the windows at lunch and my clothes smelled strongly of gas just from walking around behind the truck.

I had added a can of el-cheap-o fuel line cleaner the day I picked it up and it didn't seem to help. Last night I added 4 bottles of cleaner to a near-empty tank and it does seem to be helping some. It still idles rough and its lacking power but while driving, the miss isn't as bad.

I thought about the DPFE last night when I changed the EGR. I think at this point that I'll run it for a couple of days to see if clears back out. If it doesn't, I'll try the DPFE. I'll do a search on cleaning the EGR ports. All I have seen is the metal tube where it bolts to the EGR valve. I've never bothered to see where it goes. Can I assume, since you said "ports" that its more than just a collection point in the exhaust manifold? My understanding is that the EGR recirculates expended components of the fuel back through the intake to keep the engine running cooler and reduce emissions. Is that correct? In laymans terms anyway.

 

I don't think the DPFE can cause it to run too rich. In a speed density engine it could, but not in an mass airflow engine. If it were summer, I'd suspect the coolant temperature sensor, if bad it wouldn't be so far off i you're scraping frost.

 

Mine was missing on 2 cylinders (#3 & #4), and I definately remember smelling raw fuel in the exaust. Once the miss cleared up, the smell went away.

On the 4.6 (I assume the 5.4 is similar) there are 2 EGR ports on the inside of the upper intake (elbow shaped - one end connects to the Throttle Body, the other to the intake manifold) where the exhaust gasses re-enter the intake - mine had 2 pine cone shaped carbon masses protruding from within, which was restricting the EGR flow - hence the insufficient code. There are several threads on this site that deal with the how to of cleaning those out, although I'm not sure that the 5.4 has the same propensity for clogging. I've read that the EGR valve is rarely the culprit in an EGR trouble code, so if cleaning the ports out doesn't work, the the DPFE is the last step in the diagnosis chain.

Another thing that may help that I haven't seen you mention is replacing the fuel filter. I changed mine when all my problems began, and since it was one of the first things I tried, it didn't really help - BUT @ 190K I'm sure it was ready.

If your miss doesn't clear up, I would seriously consider replacing the spark plug/coil boots.

Oh, yeah, another thing to check is the PVC valve/hose that runs from the passenger side valve cover to the back of the upper intake - these things are prone to failure as well, and I understand that they will cause a miss/poor performance, and could possibly be the source of your vacuum leak code.

Hope some of this helps. There are a lot of good resources here, once you learn how to search.

GL,

Jamie D.

P.S. - I just read about some vacuum lines behind the battery that have given people some fits, too. You might want to try spraying WD40 back there to see if it produces any results.

 

I would say you need to look at changing the spark plugs and maybe even the COPs.

with 192,000 miles its about due for a spark plug change anyway (although this depends on when the last time your dad had them changed was) as Ford recommends changing the spark plugs every 100,000 miles but it might not be a bad idea to go ahead and do the COPs if you can put the funds into it.

 

Yeah, ditto the above - I was just assuming that someone had changed the plugs previously, and not have been a dumba$$ like me and do it @190K- talk about excessive gap! There wasn't much left of the electrode on those plugs when I finally changed them.

Troyer Performance sells a set of 8 coil packs for around $200, which is a lot less than you can get them for at a parts house. You just have to catch him when he's got 'em.