slow to get to idle

Ronald Wendt

Registered User
Tonight I towed my boat home about 10 miles with my 91 5 speed. I left it in 4th to keep the revs up and out of boost, never went over 60MPH. When I had to stop, it would hang around 1600 RPM for maybe 25-30 seconds before finally droping to normal idle.

What would cause this?

I have noticed lately that when I get off the exway after driving at highway speeds for awhile, it will hang around 1200-1300 RPM for the same amount of time before it drops.

So what might be the cause or where should I look?

Ron
 
Sounds like your heating your engine up. The ECU will idle up the engine in an effort to circulate coolant and thus cool down the engine before dropping to normal idle speeds. You're a brave man towing a boat with an SC with stock cooling system.(if its stock) :eek:
 
it could also be the coolant tempature sensor. mine was bad and it caused this and my check engine light never came on though. I have to agree mike 38 sc about towing a boat with an SC they tell you not to do that in the owners manual ( yeah I still have mine :) good luck with it .
 
MIKE 38sc said:
Sounds like your heating your engine up. The ECU will idle up the engine in an effort to circulate coolant and thus cool down the engine before dropping to normal idle speeds. You're a brave man towing a boat with an SC with stock cooling system.(if its stock) :eek:

Mike is correct here but it's not coolant temp that it's looking at, it's oil temp. If you run at higher loads and higher rpms for an extended period of time the EEC decides that the oil is too hot. My 90 doesn't have the oil_ overtemp mode and so when I used to tow my race car all over the place with it I didn't have that happen. Ignorance is bliss, lol.
 
well last night it was running a little hot so maybe that is it.

I did just recently replace the coolant temp sensor thinking maybe it was bad and causing the idle to stay up after the eway driving but it did not help. The water pump is dribbling a little so I may have been a little low but I check weekly..

And for towing, I know I am not supposed to, but here in totally flat northwest Ohio, I figure it will be ok the way I do it. I only tow it to my sisters barn in the fall, back to my place in the spring, then 5 miles to the marina in the spring to put it in and then the back home in the fall to clean it up before it goes int he barn. I sure would not tow it any distance!

Any preferences for replacement water pumps?

Ron
 
I tow a 8'-6 wide Hobie Cat sailboat weighing 400 boat + 400 lb trailer + 100 lb gear + 125 lb passenger + windage.
After my long six hour trips from GA to Florida towing the Hobie at 80 mph with stock 1990SC,
I would sometimes have high idle the NEXT day without the boat. I guessed it was because the
EEC learned a new A/F while I was towing, and used this new A/F the following day.
After about say 1/2 hour the idle would go back to normal (again, the next day).


For those towing with AOD my experience was:
The engine is TO strong for the stock AOD.
First FORD tranny (Locking TC) tranny lasted 100k.
Second FORD tranny (locking TC) tranny lasted 60k. (Probably LX od band)

In both cases, failure was due to worn out OD belt.
Do NOT accelerate to hard in OD.
Do NOT go over 5 psi of boost or the OD belt WILL slip, and BURN up OD band. :eek:
I would definitely install a tranny cooler. I did not for the first 2 trannies.
Staying in 3rd will get old. Just don't slip OD when climbing hills.

Now with Lentech tranny with 2" OD band & 3.27 (non lock TC) no slippage at all up to 8 psi of boost,
(I was not going to boost it any further) But stock engine temp gauge ran much hotter with non lock TC.
I have NOT done any towing since I installed MP FMIC/Mikes Radiator/3.55 this year.

Watch your temp gauge, and slow down if engine temp goes to high, use your best judgement.
Change tranny oil more frequently.
Check/change rear differential oil more.

.
 
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Another thing I'll add is do not tow anything with your tranny in OD, not even with a truck.
I know many people that have burned up perfectly good auto trannys because they were towing in OD, even some of my very own family members which I told not to do that. They had to learn the hard way that a new truck warranty will not cover a burnt tranny that you were towing with in OD.
By the way since those family members no longer tow with there tranny's in OD and they change fluid and filters every 12,000 miles they've never burnt up another tranny.
Sometimes you have to be burnt by the flame to truly understand that it will burn you. ;)
 
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