Hard Start/ Rough Idle on Start

[Kirby N.]

Ok, so there is 2 coolant sensors. One on the passenger side of the thermostat, which is for the guage. One on the drivers side which is for the computer. One is a sender (gauge) one is a sensor (computer).

I changed the sensor out and it is still idling at 15 when I am rolling then goes down to 12 when I stop, and still starting hard. I unhooked the battery for the 10 minutes it took me to change the sensor, and it didn't change anything. I unhooked it overnight tonight I will rehook it tomorrow and check it. The idle started when I cleaned the throttle body and MAF, so I think it has something to do with that. Can I try carb cleaner on the intake while it is running to see if I can find a leak?

It still started today by idling up to 1k, then dying after a few seconds. it did this 3 times until it wouldn't fire at all without some throttle. Then ran ok till it warmed up and started idling high. I am not sure what to make of it.

 

[Kirby N.]

Also- it has a CEL when I unplug the sensor, so that makes me think it is working correctly.

 

[2000StreetRod]

intake leak?

Also- it has a CEL when I unplug the sensor, so that makes me think it is working correctly.

I agree. If the engine is still running fast either your IAC valve is not functioning (which you have replaced) or there is an intake leak. Since the fast idle occurred after you cleaned the throttle body, I suggest that you check all of the main intake hose connections and also check for cracks or splits in the hoses. If the weather has gotten colder recently in your area then it may just be a coincidence that the fast idle began after cleaning your throttle body. You may have leaking intake manifold gaskets that shrink with cold temperature allowing air to leak into the manifold.

 

[Kirby N.]

Hmm. That does make sense. I will look it over close. The overnight computer reset did nothing. Still starting and bouncing to 1k then dying with out throttle. The good news is my iac has a lifetime warranty. I wonder if intake cleaner kills tem? I shot it up there when I cleaned the tb. I am starting to run out of ideas.

 

[Kirby N.]

A BIG thanks to 2000StreetRod. This saga ends tonight.... kind of!

I guess I should share with all of you a decision I made about a month ago.

This particular ranger runs excellent- tons of power and really fun to drive. When I got it, it needed a few things like power steering pump and lines. It needed brakes and bearings in the front and it also needed new battery cables. I thought it needed a fuel pump, which was a waste of time and money because I was trying to fix the hard start problem. I changed out various sensors trying to fix this problem- most of which are documented above.

Well, a month ago, mid getting serious about the hard start problem, I got a quote for paint. This truck was everything I wanted in a ranger except:
1. The rear fenders were rusted
2. The grey paint is in terrible shape oxidizing and generally coming off
3. It had no AC

I did a bunch of research and had actually started tearing up a exploder at a local pick and pull to rob the a/c

and I got a quote on a decent paint job... $2000. That pushed me over the edge.

Too much money in this truck!!!


So I started looking again (I never really stopped- I searched for this one for 4 years) and I found a clean 84k mile 1991 that is setup just like this one. 4.0, manual tranny and tcase. Only it has a/c and the body is nearly perfect! So I bought it for $600 more than I paid for this one @ 128K. I thought with all the upgrades I did to this one it ought to sell for close to the same.

So that brings everyone up to speed!

I listed the old one last week for $400 more than I paid for the new one, hoping to break even. Tonight I had someone coming to see it, and it was still starting hard and still idling a little high.

So I put them both next to eachother and started comparing, looking for the leak 2000StreetRod had mentioned. I didnt see any leak. However, I did see a cap over a stub coming out of the bottom of the Throttle body. I traced this on the new truck, to find that it leads a vacuum line out at the "canister purge valve" and then into the charcoal canister. The old truck had the line, but it was not plugged in to the TB and the purge valve was broke off where the line was supposed to go in.

I got a new cannister purge valve, and it fixed my start problem. it starts perfect. After it warms up, it still idles a little high, but it is not crazy high. I tried warrantying the IAC but that didn't fix it. This CPV $40 part fixed everything. So many hours and dollars!!

The end of the saga is that I sold it tonight for $25 more than I paid for the new one. So I am done. I have decided the idle is me being ****.

It has been a good truck! Thanks for all the help, particularly 2000streetrod!

The CPV made it run rich, which was causing the little poof and the hard start. Hope someone finds this instead of spending all that cash and time I did.