89 Spirit Hard Starting

[bfarroo]

My Spirit has been getting harder and harder to start. The motor was rebuilt a few years ago. Nothing major, just a refresh. New gaskets, seals, rings, bearings, ect. I've checked compression and leak-down and everything there is normal. Fuel pressure looks good also. It has a stock computer, open exhaust, TII Rad/Intercooler. It seems like it's rich on start up. It seem like if I don't let it warm up a bit before driving it It'll get a stumble where I'll have to rev it a little to clear it out. It seems to be the same whether it's warm or cold. Once warm I don't have any misfire or driveability problems. I checked the cap, wires, and rotor and they look ok, they're probably 5-6 years old now. Just put in new plugs. I was thinking of putting in a different coil but was thinking that if that was the issue I would have problems when warmed up or in boost.

[85boostbox]

Have you checked codes?

[bfarroo]

No Codes

[mpgmike]

You may have a coolant temp sensor that is out of whack. The rich condition suggests that. Do you have OS injectors? Are you running an aftermarket FPR?

Something else to look for is pull the vacuum hose off your fuel pressure regulator (especially stock units) and smell for fuel. Sometimes the diaphragm ruptures and you begin sucking fuel through that vacuum hose. The fix, of course, is a new fuel pressure regulator.

Another sign of a faulty FPR is checking fuel pressure while the engine is running. You should have no more than about 35 psi at idle. As you put the engine under load, pressure should go up. Peak pressure is around 55 psi.

Hope this helps.

Mike

[bfarroo]

I'll have to check the FPR again. I put a new one in 5 years ago but you know how parts store pieces last. It could be bad again. I'll put the scanner on it tomorrow and look at the coolant temp also. Injectors are stock. I think FP was around 45 with the vac line pulled I may have to check again.

[bfarroo]

I checked the fuel pressure it's at 52 idling. And 60 when reved. With the vacuum line pulled its 60 also. There is no gas in the vacuum line. The timing was a little high at 13-14 so I backed it down to 12. The coolant temp looks fine, 185 idling in -5 degree weather. I have 19" of vac on the scanner and boost gauge so I don't think the cam timing could be off. Ill have to see if the timing change helps at all. I have a intake temp sensor wired in but haven't done the cal for it at all. I'm running a stock cal currently. Would adding the intake temp sensor help at all?

[shackwrrr]

o2 sensor, check to see that it is "switching" from .1-.9v at idle, pull the FPR vac line and see if it goes towards .9 then starts switching again.

coolant temp sensor, let car sit overnight and check before starting, should read close to ambient, start car and make sure it ramps up to normal op temp

Hook up fuel pressure gauge and shut car off, see how long it takes for the fuel pressure to drop, check vacuum line for gasoline.

Check spark plugs for thick bright blue spark

check air filter/intake for restrictions

[DevoBuzz]

I had a similar problem once and replaced the coolant temp sensor - the one in the T stat housing not the one for the gauge! bfarroo - you said it was 185F - where did you get that value from - a gauge or from a scanner?

[mpgmike]

If you have the coil wire that lays across the engine bay it might be arcing against the engine. Look at that. Also, the terminals in the distributor cap actually contact pieces of the wires. To be a cheap skate, we typically turn them around so the rotor can contact the back side. I have seen many where the terminals weren't spread apart and slipped up and into the cap. Make sure they are protruding through where the rotor can get to them.

Mike

[bfarroo]

O2 was switching like normal, I don't remember the exact values but it was cycling rich/lean. I'll look at it again when I hook the scanner back up. I checked the coolant temperature through my OTC4000E scanner. I'll have to check the temp when cold this weekend. It held fuel pressure at 50 for quite some time when i tested it without dropping so the check valve should be good. I'll have pull a plug and check how good the spark is. I checked the plug wire ends in the cap and they looked good. The rotor had a little bit if crust at the end so i cleaned that up with some sand paper a few weeks ago. I'll check for intake restrictions but I can't immagine there being any I have a Spirit R/T rad/intercooler with a TII airbox and plumbing. I need to get the wideband hooked up, just haven't had time. I want to eventually start adjusting the tune for better mileage as this is the DD.