12-07-2018, 08:33 AM
4000RPM , the DASH pot device on the throttle is set wrong. ? may be.
first tie back the dashpot see if starts at 1000 to 1500 rpm always cold, per the IAC air openings in the base of the TB,
for sure its vacuum leak issues, 89 is old and there will be issues here, lots.
The dash pot spec , is 2500 on hot engine, if you engage the DP falsely and forced, one way to do that is start car hot.
pull the DP hose see it extend, and plug the tip of this hose with a golf tee or spare screw that fits.
the DP then extends,and it end has screw adjuster you set for 2500 RPM hot
once this is done, the DP then when cold does not go too fast. '
THE ECu retacts the DP, by command and short delay in few seconds. after keyed start.(hot or cold)
The IAC in the base is open when cold, and is the major air leak that sets cold start idle speeds.
make sure the DP is not sticking in some way.
the total air is TV + IAC +ISC + DP. 4 sources of air, I no vacuum leaks on hoses.
hoses can sure be bad this old, seen 91, with hose look like turning to TAR, nasty hoses. had 2 do that 1 on MAP hose,.
good luck and thanks for sharing.
first tie back the dashpot see if starts at 1000 to 1500 rpm always cold, per the IAC air openings in the base of the TB,
for sure its vacuum leak issues, 89 is old and there will be issues here, lots.
The dash pot spec , is 2500 on hot engine, if you engage the DP falsely and forced, one way to do that is start car hot.
pull the DP hose see it extend, and plug the tip of this hose with a golf tee or spare screw that fits.
the DP then extends,and it end has screw adjuster you set for 2500 RPM hot
once this is done, the DP then when cold does not go too fast. '
THE ECu retacts the DP, by command and short delay in few seconds. after keyed start.(hot or cold)
The IAC in the base is open when cold, and is the major air leak that sets cold start idle speeds.
make sure the DP is not sticking in some way.
the total air is TV + IAC +ISC + DP. 4 sources of air, I no vacuum leaks on hoses.
hoses can sure be bad this old, seen 91, with hose look like turning to TAR, nasty hoses. had 2 do that 1 on MAP hose,.
good luck and thanks for sharing.
(12-06-2018, 07:40 AM)WizBang Wrote: Since I did my tranny drop/clutch swap/oil-pan repaint my 89 Tracker (8V manual 4x4 2 Dr) it has been racing up to about 4000rpm on start up. It holds this rpm longer when cold (approx 2-4 seconds). It was the worst when I first started the engine after being off for about a month while doing the tranny drop, etc. That kinda freaked me out and I turned the key off after about 5 seconds of it racing at 4k. I started it again after checking the throttle cable hadn't jumped, etc. and it still did it and I shut it off again after about 5 sec. On about the 3rd or 4th start it finally dropped down to about 1500rpm after a couple seconds.
Wondered if the vacuum hoses got stretched and one cracked when the block was being tipped forward/back during the tranny re and re but I ran my fingers along and around
each with the engine idling to see if there was an rpm change. Nada
Any suggestions or suspicions?
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