'87 Reliant idles fast...

[tapeworm]

I have replaced the following on this vehicle (1987 Reliant SW - auto - A/C - 2.5L)...
O2 sensor
Coolant sensor
Fan relay
Air & Fuel filters
Checked all hoses and vacuum lines for leaks. Engine still revs to 2500-3000 RPM upon starting. Hot or cold. The electric fan runs constantly from cold start. TPS seems OK. Could the Speed/Distance sensor affect and cause this symtom? Thank you for any opinions!! -Peggy Louise

[new and old mopar man]

hello, check the wiring to the idle air control valve they usually melt on the back side of the valve cover and get stuck together hope this helps
dan

[Dean Stillie]

Sounds like it could be a TPS if the voltage isn't right to min it will think the throttle is open and advance the timing causing the idle tp raise

[six pack]

Does the"check engine/power loss lamp" work? If the fan runs immediately after hot or cold start there could be a fault code that could help you eliminate some of the guesswork. Besides some of the good suggestions already posted it could also be the MAP sensor. Was the coolant sensor you changed the 2 wire one in the side of the thermostat housing?

[tapeworm]

I checked TBS (on left side of t-body) has no corrosion and looks good. Replaced fan relay box (on drivers side shock tower) that I broke unplugging it, and fan still runs continuous. Idle does come down but still is way to high. Wires going to AIS (auto-idle sensor) on front of T-Body don't appear melted or worn. Maybe I can re-set the minimum air setting on it. I removed instrument cluster to check the POWER LOSS light because I could not get it to flash codes and found that there isn't even a socket for a bulb! So codes are not available via the on-off-on-off-on key ignition method. Should I invest in a plug in code box that flashes when connected to diagnostic plug at logic box in passenger footwell (box behind kick panel). J.C Whitney lists one at $25 for 80s and up to 97s. It does have a multi-plug hanging over the kick panel. I guess previous owner took POWER LOSS light out at some point. This is a wonderful way to spend the 4th of July! I would rather be out at the beach with all the gang but NOOOOOOOOOOO....I'm wollowing around under the hood of this Reliant with hopes of getting it road-worthy!!!!

[tapeworm]

...Also, the MAP seems to have good vacuum and electrical connection. The coolant sensor is of the two wire variety. What does that speed/distace sensor affect other than low RPM stall and the cruise control-speedometer function?

[OE812]

Tapeworm:

Isn't your 2.5L carburated (sp) and not TBI? If this is the case, check the operation of the choke and choke plate. My father in laws 86 charger had to be adjusted twice a year: once for cold weather starts and once for hot weather starts. The choke my be stuck or the "step tabs" at the choke cam my need adjusting for lower startup rpms.

Good luck,

Jeff

[tapeworm]

This engine is the TBI version 2.5L 4 cyl. (fuel-injected). I tried to get the minimum air setting on the AIS motor by disconnecting the brake booster vacuum line (creating a major vacuum leak) and waiting for the computer to idle it down but it only raced at high RPM. Hooked line back up to the brake booster and then disconected TPS and idle came down to an almost acceptable RPM. Now, when restarted the rpm's are high for a few seconds and then fall to a lower level. I'm thinking that the trouble is with the AIS motor or the TPS. Any ideas??? Fan is still a constant runner, though.

[tapeworm]

I drove the SW for awile and it seemed t run aright with the TPS unplugged. Almost normal idle wth it (TPS) disconnected. Is there any danger to the engine operation with it unplugged??? Something is definately making (or telling) the fan to run constantly, though! I would like to use the car on my 90 mile delivery route (instead of my 13MPG (in town) 3.9L Auto Dakota for obvious (Gas) reasons. I don't trust the wagon yet, though. It has 124K on it (I got it at 107K). It has ran flawlessly up to now. A greatful THANK YOU to all who have replied to my post!!! Ireally want to get this old K-car running right cause she's my "BATTLEBOX"!!!! -P

[six pack]

You definately need to get the trouble codes read. If the engine is in limp-in it will keep the fan running. Almost sounds like you could have a bad tps but without checking codes first, it would just be a guess.
The idle speed motor is probably functioning ok as you did say it revved up and then was at almost normal idle with tps unplugged.

Guess someone else fixed the problem by taking the socket out of the check engine spot. That's an easy fix.

keep smilin

------------------
70 challenger r/t conv
98 V-10 Q/C SWB 4X4
72 383 swinger

[tapeworm]

RATS!!!! I believe I may have over heated the catalytic converter by letting it idle while running so rich (trying to warm the engine up to see if the fan would kick on). I sure hope not. I put a new AIS motor on the throttle body (pintal type as this is a 2.5 TBI). Tested it by pluggng it in before putting it in TB. It extended the pintal and then retracted it slightly, when I cycled the ignition. But when I finally got the engine to sputter to life and it seems like the cat-convert. may have melted some internally. Is it possible that the culprit from the beginning was te distance/speed sensor? It affects and effects so many of the symptoms I have experienced so far? And it's about the only thing on the TB that I havnt replaced!

[speedwobble]

Correct me if I'm wrong, but doesn't the Power Loss light socket plug into a printed circuit board? If so just buy a new bulb and socket and away you go. BTW when you disconnect the TPS it will go into limp in mode. You've replaced the fan relay and the coolant sensor [hopefully the one by the thermostat] and the fan still runs. Maybe check to see if anybody has "Mickey Moused" a wire to make the fan run all the time.
You didn't say if this is a new problem or the fan has been running all the time since you got the car. I'm assuming that it's been like this since you got the car.
As for checking for fault codes, just take it to the dealer or a mechanic with a good scanner and you will get your codes.

[tapeworm]

I have no idea where the circuit board would be, to plug a socket with the POWER LOSS bulb, in to. Someone up the line has taken it out for unkown reasons. After replacing a few hundred dollars worth of parts and sensors, I have surrendered to the fact that I need to turn the old station wagon over to a mechanic that has been recommended to me. He has gotten the engine started but says it still isn't right. The search goes on and on and on and...

[tapeworm]

I finally gave up and turned the old wagon over to a highly recommended mechanic. After all the sensor replacements it seems that it had a TB gasket leak. It runs and starts fine now but at highway speed when I go to pass traffc it sputters and has no power. letting off the accelerator lets it smooth out but something isn't right. I can't tell if it's flooding or starving or whatever.

[tapeworm]

Engine now stutters when pulling out to pass. Letting off the gas seems to smooth it out but no power in the passing lane.

[Dean Stillie]

maybe it's time for a fuel pump.

[tapeworm]

Thanks to all you great people who answer the questions on this site! Your truly helpful, really good guys!!! Here is the latest solved problem with my 1987 Reliant SW 2.5L Auto:
High speed stutter when passing. When I checked the Hall Effect and found the plug wires not fully seated in the dist. cap I was dumbfounded. The mechanic had not pushed the rotor contact blades on the end of the plug wires all the way in. I seated them and the car is now back to BATTLEBOX status and surprising the Corollas and Nissans unfortunate enough to underestimate my K-car SW sleeper at stop lights!!! Now I must find out how to stop the tranny drip which is leaking (2-3 drops a day) at the point where the engine-transmission join. (Rear-seal?) Sounds like another learning project to head off a problem down the road. Thanks again to all the helpful folks!!!!