RAIN = REALLY FAST...NO RAIN = REALLY SLOW

[HITMAN_SHO]

ok here's the deal. i've got a '91 plus, just rolled over to 100,000 miles the other day. i've been having this problem with poor idle, power loss, engine running hot (not according to the gauge, but the heat pouring out of the engine compartment). now get this:

the other day, it was rainy outside, and after about a 100 mile trip, i got on it when there was dry pavement. (it was raining miuntes before, kind of out of town, so it didn't have a whole lot of time to dry off i guess...) it's power was back! when i first got the car in march, it couldn't have performed better. that other day, it felt faster than it ever has. much faster than it's been recently...it just buried me in the seat. SO, something got wet. another factor i though of is it was 65 degrees outside, alot colder than it's been in awhile. but after i got home, i hopped in the car 10 minutes later to go to taco bell...and it was slow again.

ok another problem. it usually takes like 2 seconds to start the car, but every once in awhile i'll let off the starter early, so it doesn't start, but when i turn the key again, it turns slow, it's DEFINITELY fighting against advanced timing. i know that problem when i hear it.

i've replaced the cps, the maf sensor, timing belt (yes, installed right, verified 3 times now), water pump, spark plugs, O2 sensors, and probably a few other items i can't remember. (to fix the idle problem, and of course, that preventative maintenance)

ANY HELP WOUD BE GREATLY APPRECIATED! thanks in advance everyone!

 

[SolidState]

I have noted that my car feels quicker when it is damp out...

 

[billyshoe]

you guys are rainracers

 

[Mr Anonymous]

Codes?

 

[wood_e]

Could it be that the damp air is more dense and since it rained probably colder than the air was before?

Just a thought.....

 

[SHOtimer]

Did you replace your plug wires with all those other things, I didn't see them. How old are they? If they are over due they could be playing a role. Other than that it seems you have a strange situation at hand.
Doug

 

[Dr.Evil]

My 90 does the same thing...only it doesnt really matter how hot it is or how damp. Sometimes it is just faster than others. To try and figure it out, along with my not believing it is living up to potential (cant even do a burnout if I wanted to) I have replaced:
TPS
CPS
CID
MAP
MAF
timing belt
plugs
coilpack
y-pipe/exhaust
computer
Intake
intake gaskets
front brakes
All of this has helped a little but it is still not nearly as quick as my 89. Last things I have to try is a bigger MAF, new wires, valve adjustment and a compression test. I think it may have a bad cylender or the valve lash is off. please let me know if you find out what is causing it.

 

[sdpatt]

I agree. Got any codes? That's not much information to go on.

 

[SHOoff89]

I know exactly what you are talking about with the starting thing. Mine does the same thing, and for the life of me I can't figure out what is causing it. Somebody out there must have had the same problem.....

Anyone?

 

[HopefulSHO]

If you need any help poking around, I'll lend a hand. I don't live too far from ya.

 

[SolidState]

my car throws no codes and is getting healthier by the day, but it does seem peppier in the rain...

 

[93EmeraldMTX]

my car will take forever to start if i dont let the idle settle down all the way back to 700. if i turn it off while its still floating around 1200, it will take alot of cranks to start.

 

[HITMAN_SHO]

well it was noticeably faster not just "it's a little cooler outside and the car feels a bit better"...but it was performing significantly better than it ever has

as for codes, i think the last time i ran them i got the same ol' mass air flow sensor output voltage too low...and i forgot to mention this...when you unplug the MAF sensor while the car is running (and idling like crap), it idles perfectly...but taking it on a test drive with the MAF sensor unplugged, it likes to die. i just thought i'd point that out. like i said the MAF sensor has been replaced, because my UN-trusty old chilton's book told me to do so (when there's MAF sensor voltage problems)

as for plug wires...not yet...no misfires, but pretty soon i'll have to break down and get some new ones. there's no oil in the wells, i've fixed that problem =)

yet another thing i'd like to point out, is after i start it in the morning, it will idle from like 500 rpm (missing like no other, TIMING IS WRONG), and then it will rev to like 2,000 rpm (idles perfectly @ that rpm)...then back down again, then back up again, etc. until the car has warmed up. then it goes to crap idle constantly (says like 700-900 most of the time, sounds like it's 400 b/c it's missing so bad)

i have access to a new CID sensor, or cam sensor, from a local SHO enthusiast...he's gonna let me put his good one on, to see what it does...and i'll do that tomorrow. i'll keep you updated. thanks so far everyone, but keep it coming!!!

 

[EHBOY]

Yeah, this has happened to me too! I've an 95ATX and when its just rained out it seems like it wants to take on the world... every time! It badly needs the 60K too!

 

[philw349]

a 60k is the key for these engines. It sounds like advice your mom gives you but it makes sense. Part of the engines performance comes from having mechanical valve lifters instead of hydraulic (I believe that's the terminology). The valve lash being out of spec is like putting a cam in your engine thats designed to take away power. It has the same principles involved. But additionally theres parts in there designed to wear out to save the cams, and they will wear out.

 

[HITMAN_SHO]

rain wouldn't cause valve lash to temporarily be adjusted. the rain was just a sign that my SHO is capable of pulling alot harder, what would rain have to do with my valves being out of spec? and also, the timing is off. like they say, timing is everything.

i had a '68 LTD with a 200,000 mile original 390 in it. put a new timing chain on (old one was stretched and sprocket teeth were worn really bad), and it did a burnout in 3rd gear @ like 105mph with posi on a dry rearend....it would almost have trouble in 1st gear before. it wasn't raining that day wink

 

[philw349]

Sorry my post was more meant for Dr. Evil, who seemed to think his valve lash might be off. And I was just gonna say if its due for a 60k go for it. I don't know what to tell you about the rain. Raining usually means cooling off (especially in hot weather) which can = more power. I've typically noticed more power at night cause it gets real hot here during the day.

 

[HITMAN_SHO]

well yeah the 60k does affect performance. and i appreciate the recommendation. but it felt 1/3 faster. what i think is that something got wet, and things changed.