Throttle lag and persistant stalling after restart from hot

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stincoln

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Hi There
I am attempting to sort out some issues with a '98 LSC that I bought last summer and have just put back on the road after storage.
I've run about a tank of premium through it and had Stabile in the tank for the winter so I'm pretty sure it isn't a case of bad gas.
After about a 100 mile run I stopped for about 15 minutes and then when I attempted to restart it would start but as soon as the RPM's started to drop it would stall for about 15 tries. Pumping the accelerator didn't help and now I have a check engine light. Sorry I can't give codes but when this happened last summer before I put it away I had it in and replaced the #4 COP. It seems to me this might be the same problem again except I notice that when I am at speed and take my foot off the pedal the RPM's take a while to drop. This has me wondering if the IAC or TPS might be the issue...mileage over 200 miles was about 18.5 according to the message centre which also made me wonder if there could a vacuum leak.
Just to whine a bit about Canadian prices for the same brand parts... a Motorcraft IAC is over $100 while I see it for about half that at Rock auto.
Any suggestions about where to start?
Thanks
Des P.
 
Thanks for the reply...are you thinking the fuel pump would be related to the stalling specifically or the lag as well? I only seem to have the prob after it has been heated up as in going through heavy stop and go traffic in Toronto last summer.
 
Start with the basics. Check fuel pressure have the parts store pull the codes and inspect everything. Pull the plugs and inspect.Then come back and report
 
Buckeye68 said:
Start with the basics. Check fuel pressure have the parts store pull the codes and inspect everything. Pull the plugs and inspect.Then come back and report
Click to expand...

I concur, but wanted to add that the slow fall back to idle was a bad IAC on my car. The previous IAC was only a year old and was the cheap one at Oreilly, I'd suggest buying the motorcraft if it comes down to the IAC.
 
I say it is the IAC because he is stating it only happens when the engine is hot and at restart, very common with the IAC.
 
Yes but the engine will still run if you are pressing the gas peddal if the IAC is bad. He states he presses it and it still stalls which would lead me to believe fuel pump... or vac leak.... or bad plugs..... or dirty fuel filter.... could be lots of things. Its so hard to diagnose online without hearing the car.
 
True to that it could be anything, and not being there is hard to tell. But I do know that a IAC will do as he states he is experiencing and it will stall even if you give it gas, the engine will spit and swallow like a whore in a alley, and may need a couple of starts to clear out.

Just saying you lil tic turd. ;)
 
Last edited:
LaserSVT said:
Yes but the engine will still run if you are pressing the gas peddal if the IAC is bad. He states he presses it and it still stalls which would lead me to believe fuel pump... or vac leak.... or bad plugs..... or dirty fuel filter.... could be lots of things. Its so hard to diagnose online without hearing the car.
Click to expand...

+1

But its easy to check fuel pressure, check codes, go from there.
 
Hi Guys
I'm a long time getting back to this but I thought I owe Laser the satisfaction of knowing he had identified the problem correctly in the very first response...Buckeye deserves honorable mention because if I had checked the fuel pressure instead of just following the codes I could have saved some time and money.
1-replaced IAC
2-replaced MAF
3-replaced plugs
4-replaced 4 more COP's (thanks Jay!)
5-replaced fuel filter
6-checked fuel pressure(10 lbs!)/ replaced fuel pump = happiness
BTW the pump was a Walbro so it had been done previously, replaced it with the only one I could find locally an Airtex from NAPA for $125...it's been an expensive puzzle
 
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