1990 Ford Tempo



December, 12, 2012 AT 9:36 PM

Engine has eratic idle and lurches after it warms up (20 minutes). The Ignition module was replaced 20,000 miles ago. This is a follow up to my original question from September 6, 2012.
Here is what I've done on the car since then.

1990 Ford Tempo (4 cylinder) Today’s date Dec.11, 2012
2.3 L - manual transmission
VIN # 1FABP35XILK234531
Odometer – 245 270 km

Vehicle in trouble since Sept. 6, 2012

Thanks for the initial comments.

I can’t take it to a pro as that is not a financial option for me. I would be prepared to pay 20 dollars for some advice that allows me to know what the problem is, so that I can fix it myself.
I can reproduce the “lurching” referred to on September 6 – 2012. It seems to only occur after about 20 minutes of running (either by driving it or letting it idle). The lurching, once it starts is quite persistant and eventually will lead to a stall unless I use the gas pedal to keep the RPM up while stopped. I thought I had the problem solved when I presumed it must be temperature related. This presumption pointed me to the cooling system and I found that; a) system not holding pressure b) rust colored antifreeze observed though Radiator Cap c) thermostat may not have been working.

I have since;
1) replaced a leaking hose (thermostat to heater hose- toward firewall)
2) replaced thermostat and radiator cap
3) Flushed the system quite a few times with water and also with “Prestone super flush”(the rusty liquid had gel-ed in the antifreeze reservoir so I thought it important to repeat the flushing)
4) Engine Coolant Temp. (ECT) sensor changed.
5) Replaced the Air charge temperature (ACT) sensor in the intake manifold.

Basically, I have made sure the system is being cooled properly
[ thermostat opens when warmed, and results in the cooling fan turning on (fan switch works). Also the water pump is working as I feel the pump pressure when I hold the upper radiator hose], Yet the problem persists.

I have redone the Trouble codes test.
Two outcomes result; they now show the following;
1) if I perform the test prior to 20 minutes of idling.

“0” or (Key On Engine Off ) KOEO codes;
11 - system Ok

“C”(continuous memory) codes;
14 - Ignition profile pickup is eratic

“R”(engine running) codes;
11 - system Ok

If I perform the test after 20 minutes of idling,
the Trouble codes show the following;

“0” or (Key On Engine Off ) KOEO codes;
11 - system Ok

“C”(continuous memory) codes;
14 - Ignition profile pickup is eratic

“R”(engine running) codes;
Either the code below would be indicated (if engine didn’t stall)
13 - Ignition profile pickup is eratic
and RPM would fluctuate between 1800 and 500 RPM.
if engine stalled, the following code would be indicated
77 - Goose test not performed

If anyone has experienced these symptoms or knows what this problem probably is, I would appreciate communicating with them.
Any information would be helpful.
The frustrating part is that the car works perfectly for the first fifteen (or so) minutes.

Thanks in advance,


2 Answers



December, 22, 2012 AT 9:33 AM

I have had tempos for years and do recall such an issue but so long ago dont remember the cure. Does it drive fine when this starts happening? Loopy idle is usually LEAN mixture problem. Check cold and warm pump pressure. How do your plugs look? How new are they?Do you have MAF or MAP sensor?MAF's are known to cause these issues. PIP is in the distributor electrics so the cheap way to try something is to replace whole distributor assembly with 1 from boneyard. Hope your area has such old cars still. Although ebay or other internet sources may prove useful. Or just replace the TFI and HALL unit in/on yours. I have not had but 1 bad 1 that I can recall in a lot of miles/cars.



December, 22, 2012 AT 9:40 AM

I guess you checked for vacuum leaks? You can try unplugging temp sensor while it's looping and then OX sensor. An intake leak might cause this but I would think it's sorta rare. It sounds like your IAC is causing the loop by hunting for the right air mixture to keep car running. You could unplug it and see how it acts when warm.

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