Junkyardjeff

My 88 bronco with a 5.0 has never really started good when cold and starts easier with the gas pedal slightly depressed,could it be the TPS.

wde3477

Suggest it may be one or more of many things.
Consider your vehicle is 27 years old now. Perhaps the injectors are not spraying as they should, either through being clogged or low fuel rail pressure. The extra air provided by the gas pedal being depressed may provide enough turbulence or higher combustion temps to light off the poorly volatilized fuel...??? Or perhaps a spark not quite hot enough...?

Chris_1

iTrader: (1)

I'd look at the TPS and the ECT. You can test the TPS, the ECT is cheap just replace it.

Junkyardjeff

I do not think I ever changed the plugs and who knows how many miles are on them,the wires and cap have been replaced and will check the fuel pressure again. I also was told worn injectors could cause this problem but I do not think I have ever put any cleaner in the gas so I will do that first.

fltdriver

Run the entire tank w/cleaner in it, also suggest getting some spray seafoam and following the directions, if your plugs are that old there is probably a nice layer of deposits in your engine from unburnt fuel. Once you get that done then change your plugs, it would be a good idea to do your oil within a few hundred miles as well because the seafoam will loosen some gunk, bare minimum at least change your oil filter and replace lost oil.

Martian

Regarding cleaners, get a GOOD one. Avoid Lucas, MMO, and SeaFoam (SeaFoam is great in the intake / vacuum lines, doesn't do anything in the gas tank).

Stick with Gumout With Regane (Gumout without Regane does nothing), Techron, or Redline. They contain the best concentrations of polyetheramine, the only true fuel system cleaner.

Junkyardjeff

Its amazing on what a fresh set of plugs does,it still wants to surge a few seconds after starting when cold but fires right up.

Toplait

Could be TPS but I would check for codes first before replacing stuff...Or pull the old trusty meter out and test that voltage. You'll most likely have to take the throttle body off.....Gasket is reusable if you take care not to bust it all to pieces.

Change the fuel filter you have not done in the last 30k miles

Clean the Idle Air Control Valve...It connects on the driver side....Make sure you put it back the right way.....If you decide on cleaning the throttle body.....Newer styles had a protective coating inside them, "which you do not want to clean." Not sure if yours does.

Also, give it a good tune up if not done recently....Then advance the timing to about 13 degrees with spout out.

Check the slack in the timing chain...Pull the cap off the distributor..Leave the Rotor in...Turn the crank left and right with a socket and wrench...The rotor should turn soon as you move the crank left and right...If it has a delay...Replace the timing chain.

Make sure your battery cables, terminals and connections are clean and not corroded going to the battery to the starter.... That starter should roar on over. Clean all ground connections going to and from motor. You'll have to use a wire brush and take stuff apart.

If your using the factory original battery cable going to battery to starter...Replace it. I bet its pretty corroded under that plastic.

Check fuel pressure, make sure your getting around 35PSI with key on engine off...Then have some one crank it over and watch fuel pressure.... You should be getting max of 40-44 psi max depending on engine RPM if I remember correctly...

Vacuum lines: Make sure all vacuum lines are in good shape not busted ect...

O2 Sensor...If you have the factory O2 sensor still in...Replace it. You'll be surprised how much crap is stuck to it. Better gas mileage... You should be getting around 15mpg.

Clean all wiring connections... Even clean the Main computer wiring harness connector going into the computer.

If I missed something or if something is incorrect please chime in...

Junkyardjeff

I think it still has the original O2 sensor and at 190,000 miles it might need to be replaced.