Anyone had this happen??

[SpiderJim]

Just got hold of a another 81 Fi spider. Last week I drove it from Vegas to Canada approx 1500 miles. Weather when leaving was around 75-80 deg and dry. After the first 200 miles I was climbing a low grade slope for several miles doing about 65 mph. All of a sudden I get a hiccup and the engine seemed to cut off for a fraction of second. Another mile and same thing again. Monitoring this situation it seemed to happen about once or twice an hour and always at similar cruising speed. Car started great and idled okay when warmed up but not good when cold. Finally headed through Seattle after rain in Oregon. Stopped for the night then headed for the border. Hit the Canadian border and weather is now over cast with occasional rain similar to half the trip that I had the odd hiccup with. Temperature is is around 50 deg or so. Now around 100 miles from my home when I start to get longer cut offs and more frequent events. She kept running but was now getting worse. Once while getting a lot of the cutting out I hammered the throttle to see if it was fuel starvation and it seemed to respond quite normal. I have a theory that may be stupid but here goes. I had just redone the timing belt, tensioner bearing etc. When I had it all back together I refilled and bled the cooling system. While at idle a hose blew off cause I had missed tightening the clamp (bad boy!) I refilled and re-bled. While driving it occurred to me that I may not have opened the heater valve the second time around due to panic setting in that my friends garage floor was getting a hot bath!. Here is the rub? Is it possible that when I hit the colder climate and began using the heater that an air pocket was passing through the system and may have momentarily trapped at the T junction where the coolant temperature sensor is monitoring the coolant and that the air pocket could possibly screw up the Temp and info sent to the ECU as it passed over the temp sensor???

Unfortunately I had done a lot of work to the car prior to the trip that was all new parts replaced. Following is some parts that could have something to do with this. Any ideas would be very much appreciated.
Installed
New Dizzy, Mag P/U rotor cap etc.
Fuel pump
Coolant and all hoses
Cleaned all grounds, Fuses and connectors.

I did notice that the PO had been digging around the AFM but I reset and tested it to factory specs. Still starts great but idles like crap until warmed up. Had it out today and random cut off at take off and city street speeds so maybe getting worse or is it that a Vegas car just hates the BC winter weather?

[racydave]

No, cauz when there is air trapped, there is not any flow, or heat either, and would overheat the eng.. Id bet on a ign module.

[mbouse]

the trapped air is gonna collect inside the head, not at the T-fitting. sounds electrical, and most likely in the ignition circuit.... but wadda I know? it's a F.I. car and i hate computers.

[jpmilesdds]

Just a guess:
Your fuel pump is cutting out. The fuel pump relay is very unreliable (ask the folks at IAP.) And the air mass sensor has some easily disrupted parts. In 30K miles, I've had the relay fail twice and some important contacts inside the air mass sensor become uncontacted. If you hot wire the fuel pump, the problem should go away, but realize that this creates a fire hazard in an accident and will wear out your fuel pump prematurely, so don't leave it that way.

[SpiderJim]

Well I believe I have found the gremlin. Today I removed the AFM and to take a good look at it. Before I left Vegas I had noticed a very slight grating sound when moving the flap at around the idle position. I had dived into the AFM to reset the pump switch arm that the PO had adjusted to the left so the pump would run continuously. The noise was so slight and me not being that familiar with the AFM guts is that I put it down to the flap shaft needing a bit of lube. So this is what I think happened.

Vegas temp was hi 80's and except for a touchy low idle setting that seemed to forever change everything seemed pretty good. Heading for Reno and about half way climbing to the higher altitudes is when the hiccup began as the temperature dropped. As I got further North the temperature dropped rapidly along with rainy weather. Today when checking the AFM it was really sticky in two positions. One being around idle and the other being approx mid way to the full arc position. Made the same grating noise that I noticed in Vegas but this time definitely sticking. Seems the flap is slightly warped on one edge and needed adjustment and a bit of filing down. Now it is free and no grating and will install tomorrow. I believe that the tolerances are so close that leaving the warmer climates the metal had shrank a fraction and the sticking got worse as I really noticed it being so.

Having read a couple of post today that I finally came across had the same hiccup problem going up hill at cruise speeds. The flap was sticky both around the cruise and definitely at the bottom idle position area. Due to only noticing at mainly cruise until close to home I never related the flaky idle and the hiccup to be one and the same. Just as a matter of course the idle had to be set at around 1500 rpm else to keep it steady. I could go lower but the engine got really rough and hunted all over the place. When decelerating if I had to stop quickly the idle would slam down and almost die. However, if I decelerated slowly allowing the RPM to fall off gently the idle would settle at the 1500 rpm as set. This all makes perfect sense now. The idle was hard to set lower due to the bloody flap stick ever so slightly. I know this is long winded but details may help the next poor sod who runs into similar issue. Thanks to all of you folks for taking the time to help us new guys get to know our cars.

[mdrburchette]

Thanks for taking the time to document your fix, Jim. It may help someone else that has a similar problem in the near future....namely me. My X19 has been acting in a similar fashion but hiccups so infrequently and quickly, I don't have a chance to react. I now know where to start at least.

[SpiderJim]

No problem I'm glad to give something back as I think this board is the absolute best thing since whipped cream and a las vegas show girl.. Mine was definitely worse in the colder climate. So it fooled me at first due to driving a long distance in a short time with 30-40 deg ambient temperature change that tightened everything up. Have fun!!