hard to start after 10 or 15 min or more

[jeremy manlief]

i have a 95 mtx. it is hard starting(cranks for about 5 to 10 seconds) after you let it sit for 10 to 15 minutes or more when it is warm or hot. it starts fine when the engine is cold. when it does start up when the engine is warm or hot, it stumbles and misses for a few seconds then it idles just fine and runs fine. it starts just fine when the engine has just been turned off and you start it again, but if it sits for 10 to 15 minutes or more it cranks for a while. also, when i am driving it, off throttle response is terrible. when i am in a gear and you let off the gas completely, the engine seems to fall on its face and the car jerks forward. it doesnt surge or anything. it seems like the rpms arent staying up when you let off the gas to give you a smooth off throttle response. maybe vss problem. this is noticeable in all the gears except 5th. it doesnt do it that bad or not at all in 5th gear. there is no codes with the koeo and koer tests. i have put about $2500 in new parts in the car and everything i put in it is ford parts so just about every electrical part has been replaced. any help on these issues would be great and if you need some info, let me know.

 

[GreenStreak]

I had the same problem with my SHO for a few months. It wasn't my daily driver, so I didn't bother with it until late. Like you said, car would start cold, but after warming up for 10-15 minutes, you wouldn't be able to turn it off and restart it until it cooled down again. As I expected, it turned out to be the starter. After replacing it with a new Bosch unit, it works great, and I have no more warm start problems.

As for the surging and jerking during deceleration, my 92 MTX does it occasionally too, but it doesn't seem to be as bad as yours. I usually get a nice deceleration, with it slowing down more in the lower gears as it should.
Sorry I can't help you on this one though.

Yay! My first post here. (But I have been active on TCCA for over two years now, and just lurked around SHOForum)

-Rob

 

[MilTownSHO]

Sounds almost like you could have more than one problem there. CID replaced? It's an easy and cheap fix. Does your tach ever not work temporarily? That would be a good sign of this.

I would say CPS but it does restart everytime even when it takes longer right?

 

[sdpatt]

I'm hearing of a possible heat-related fuel system problem. The fuel pressure from the pump may be lower when the pump is hot or the fuel pressure regulator may not be correctly controlling the pressure when vacuum is changed at startup and lift throttle.

Have you seen the CHECK ENGINE light illuminate lately? There may be more than one cause for this situation as you mention that you have replaced many parts. Pulling the codes would be the next step if the CE light has appeared.

 

[shojuan]

Yup, sounds just like the early stages of my failing fuel pump. Never threw codes. Just a long, long, LONG downhill road. Actually it ran crappy like you're experiencing for a long time, pretty consistantly in hot weather with some reprieves in the colder weather.

If checking the codes like Scott mentions doesn't point you towards other suspects then suspect that fuel pump.

 

[jeremy manlief]

thanks for the replies. i will try to answer everybody. the cam sensor and the crank sensor have been replaced with ford replacements. there is no codes present and it hasnt come on since i did all the work to my car. the CE light did come on before i did the work. cant remember what the code was but it had something to do about a 2nd fuel pump circuit or relay, but no CE light since i did the work. i was leaning towards the reply from sdpatt. it seems like a fuel issue. my SHO has 145,000 miles on it and as far as i know the fuel pump has not been changed. i havent checked the fuel pressure but maybe i should. the car is still running great and i havent noticed any decreases in power. outside temp doesnt seem to affect how it starts or runs. it does seem like it misses when its around the 2500 to 3000 rpm range, but thats only when your shifting from 1st to 2nd and sometimes into 3rd(engine hot or cold). any ideas on my off throttle response or do you think both problems are related.

 

[sdpatt]

A misfire without any tell tale error codes is either the spark plugs or plug wires. How old are those plug wires and what plugs are installed?

 

[jeremy manlief]

there is brand new spark plugs and wires. both are ford factory replacements and the recommended parts from ford. also brand new valve cover gaskets and plug well seals with no oil leaks. its not really a misfire, more like a hesitation at those rpms.