I've lurked here and on other Ford forums quite a bit, and I'm stumped. I can't figure out what is causing this hesitation on startup. On the first start of the day, it starts slowly, but starts on the first try. The warmer the truck gets, the harder it is to start. I had my battery and alternator checked, and they were both good. I also replaced the starter solenoid, and still no dice. I also had codes ran on my CEL, and the majority of them were relating to my O2 sensors, possibly because I'm running without an exhaust since the cats were clogged...but that's a completely different can of worms .

Also, the timing was jacked up when I bought the thing, but that was addressed before I drove it home. So aside from replacing the starter, I'm fresh out of ideas. Seems obvious, but then again, I have no idea Any help you guys & gals can give me will be greatly appreciated. Thanks

 

well i hope your not driving it at all right now.

if the starter is dragging then you either have bad battery cables or the starter itself is beginning to fail. The timing also plays a major role here, the timing must be set to 10*btdc with spout connector removed. this takes the advance out of the timing for it to be set properly. if its not the motor wont start well.

Next is the o2 sensors, with out those your motor is probably dumping alot more fuel into the motor because it doesnt know what the system is doing. This can RUIN a motor fast. if your exhaust is falling apart, go to a wrecking yard and pull the exhaust off of the same year bronco with the same motor. bring a cordless sawsall in case you need to cut before or after the cat on that rig.

 

Give us some more info, year of bronco. Has it sat a long time. Mileage. Any other symptoms, etc...

 

It's a '96 XLT, 5.8 351W E4OD, 188,??? miles, and has been sitting for about a month according to the prev. owner. Once it gets started it runs fine, haven't had any other issues with it as far as the engine is concerned. I also forgot to mention that the battery terminals were corroded to hell, so I installed new ones, and had to cut & splice a section of new cable for the positive wire due to the corrosion being so bad.

I drove it to work today because I already had an appointment set up with the exhaust shop in town to turn it in, plus my bike is leaking gas everywhere, you know...because I don't have enough problems already . So much for keeping the mileage off my other truck so I can sell it, but I guess I gotta do what I gotta do.

 

that model is obd-II. it has to run with 3 o2 sensors. 1 in each side of the Y pipe and then the 3rd o2 is inbetween the first and second cat converter. If you install 2 hi flow cats have them rebuild the y pipe with 2.5" tubing and run 3" exhaust out stock location. might as well rebuild the whole thing. fyi magnaflow hi flow cats are less then $100/ cat on summit. no reason to spend more than this.

I would also replace those battery cables. RJM Injection Tech — Welcome is a great resource for these types of parts. good quality.

 

That's pretty much exactly what I'm having done. 2 Magnaflow hi-flow cats, new pipes, glasspack, and labor is gonna run me about $670. Wish I had the equipment/knowledge/space to do this myself Anyway, once I get it back from the shop, it's gonna sit underneath my carport until the weekend so I can give it a proper tune up. I'll do everything I can before I officially surrender and hand it over to a mom & pop shop here in town. And the saga begins........

Again, I appreciate the help thus far

 

when it comes to exhaust i leave that kinda work to the proper folks so dont feel bad, its just not worth saving money doing it yourself.

you might find that glasspack on the overly loud scale. I run a hooker aerochamber, sounds awesome on the throttle but once i back off it quiets down and doesnt drone inside the cab.

good luck with your tune up.

 

Your hesitation during hot starts and lack of fault Codes relating to thermal issues answers the question. The most likely culprit is the ECT sensor (mounted in the water neck above the thermostat). Run a search for it, I think I've troubleshot this problem about a hundred times. There is a good reason you aren't getting a fault Code for it but I'll spare the gory details. You can find the "why" if you do the search.

NOTE: The ECT sensor is NOT the temperature sensor for the dashboard gauge! The ECT has three wires running to it and is mounted as previously noted.

 

Funny thing is that I did search, but I guess I had no idea what exactly to look for....... At least now it makes more sense to me why it wouldn't be the alternator or starter like I originally thought. I'll definitely look further into the ECT sensor, thanks greystreak92. Back to O'Reilly's I go.....

And Kemicalburns, I have a 2007.5 GMC Sierra 5.3 with Flowmaster 40s on it. It's kinda like your Bronco in that it sounds great on accelleration, but not loud enough to drown out my radio or passengers. I love the tone of it, but just wish I could somehow turn up the sound a couple notches without sacrificing sound quality. My Bronco on the other hand.....the louder, the better!

 

Sounds like the same symptoms I was having this spring with my 89'. In my case it was a bad positive battery cable from the battery to the starter solenoid on the fender

 

The more I think about it, the more I think I might need to start looking for a new wire harness. I mean, I cut a pretty good section of my positive cable off already, and spliced it with some new wire, but I think all I did was put a band-aid on the problem...and it's already gotten soggy and fallen off the wound so to speak. I'm afraid the corrosion may have already taken its toll on my battery cables. Guess I know what I'm doing when I get my truck back from the exhaust shop (sigh)

Edit: On second thought...maybe I should just worry about the battery cables for now, and hold off on the entire harness later. I just wanna drive the thing. I'll worry about the wiring hackjob that went into this kid's mad tyte concrete shaker sound system later, which has been immediately disconnected once I brought it home.

 

i agree, start with the cables first. I would change out the negative and positive together. that link i shared has a great do it yourself kit so to speak. Its on my list for sure.

 

I agree with these guys Kemical and GS know a little somethin somethin about these trucks. Me however, since i have a carbed engine i can't relate to this besides the fact that i get a slow crank when it has been ran hot and started multiple times. Since gas here is almost at $4/Gallon i don't drive very much anymore. Since it seems you are pretty set on getting Glasspacks on there, i hope you know what your getting into i have dual cherry bombs on my 78 and it doesn't sound all that great. I like the lower tone and the loudness for the most part but when you step on it, it sounds like an airplane. I hope you don't run into this issue as well. Of course with my truck, i have some crappy flex tubing as my exhaust pipes so that doesn't help.

Anyways good luck with your project.

 

Alright, so as far as preventive maintenance goes, I changed the oil, spark plugs, plug wires, and air filter on the truck this weekend. My appointment at the exhaust shop has been pushed back until tomorrow, so hopefully that will be the end of my CEL staring me in the face. And since I'm paranoid, since my exhaust was already screwed up, should I go ahead and replace all 3 of my O2 sensors whlie I'm at it?

 

if you decide to replace the o2 sensors go to ford if you can afford it.

what spark plugs are you running? any copper plug is the way to go, like motorcraft or autolite.