Multiple codes

[RiverDog]

I have a 96 Ranger SC 4x4 with a 4.0, automatic, and 90k miles. I haven't ran the truck for two years and just got it on the road again, sort of. I replaced the plugs, wires, and coil pack. I'm getting a P174 and 3 misfire codes, 303,304, and 306. It does a lot of backfiring as you drive and seems to be a little (but not much) better when the overdrive is off. This is why I parked it in the first place. I have put two cans of seafoam through the system with little change. I have a new fuel filter but didn't put it on yet. I pull a steady 18" vacuum and it responds normally if I goose the throttle. Where do I start looking next?

 

[modelageek]

no expert here. but let me start it for you. thinking out load, did the misfires cause the lean condition or did the lean condition cause the misfires. you dont have the 171 code so that might mean something. I would start off with cleaning the maf and looking for vacuum leaks, you have misfires on cyl 3, 4 and 6 that means you have misfires on each side of the engine, right? you replaced the coil. I would think that since you have misfires on both sides it could be the maf a vacuum leak, or fuel presure issue. maybe you should replace the ff. might want to think of doing a fuel pressure test. I am wondering if you kept driving the 171 code might get thrown..... let see what other peeps think.

 

[modelageek]

more thoughts after reading it again. you got good gas in there correct?. I would throw some injector cleaner in the tank. I am suspecting clogged ff or fpr or fp issue. doe sit start right up do you have to cycle the key a few times to get it going.?

 

[eastwildlife1965]

Start from basics. Do a compression test. Ensure you have a fresh plug and a good wire to the cylinder, check fuel pressure at the rail, if all check out good, use a stethescope or long handled screwdriver to listen to the injectors and compare them to a known good cylinder. Should they all sound the same start checking for vac leaks on that side of the engine.

 

[modelageek]

I try to look at this practically and i agree a compression test is always good to do , however most people don't have a compression tester. I also doubt it is a compression issue because that would mean 3 cylinders have a compression problem. highly unlikely.

 

[RiverDog]

I haven't done a compression test yet and I do have most test equipment. The tank was nearly empty so it's full of new fuel. I have a stethoscope but I'm not sure if I can get to the injectors. This weekend I'm going to pull the injectors and see if they are plugged. I also will put on the new fuel filter. I am thinking it is a fuel related problem but not sure. I did clean the maf but nothing changed. I drove about 15 miles and still only got a lean code for the one side. It fires up immediately and seem to idle fine. If there is a vacum leak the new gaskets should fix that unless it's a hose but I haven't been able to find any yet. Thanks everybody for the quick responses.

 

[modelageek]

I dont think it is a compression issue or an injector issue. I think it is a fuel pressure issue, a vacuum leak or maf issue . you checked the air filter and you dont have a oled air filter correct?
keep us posted

 

[SoLongStang9499]

I second looking for vacuum leaks, 18Hg sounds too low, it should be sitting at about 21 or 22.

 

[RiverDog]

The air filter is almost new. I'll check again for a leak before I tear it apart. Any tricks to finding them?

 

[modelageek]

Spray carb cleaner with engine running if it revs there is a leak

 

[RiverDog]

I checked the fuel pressure and that seem to be good. I sprayed a full can of carb cleaner everywhere and the engine speed never changed. I had the vacuum gauge hooked up while I did that and it stayed steady at 18". I don't know where to check next, any more ideas?

 

[modelageek]

I checked the fuel pressure and that seem to be good. I sprayed a full can of carb cleaner everywhere and the engine speed never changed. I had the vacuum gauge hooked up while I did that and it stayed steady at 18". I don't know where to check next, any more ideas?

what was the fuel pressure did you check it with running and not running?

 

[Bird]

Your problem is probably spark related - a misfire will cause a lean condition - 2 cylinders misfiring on one bank will definitely throw a lean code for that bank (ie174=bank2=#4&#6). Start it up, rev it until the misfiring starts and immediately turn it off and pull the plugs for #4 and 6 - you'll probably find them sooty and possibly wet with fuel. Did all this start after a plug / wire change?

Bird

 

[RiverDog]

I had around 65# and it dropped to about 50# when I started it. I changed the wires and plugs because of the missing. I don't know what else to look for. I hate (can't really afford) to take it to a dealer but it's starting to look like I might have to.

 

[modelageek]

I don't think it should drop that much.