1993 Ford Escort 1.9 Litre

[Jonny H.]

This is the 1.9 liter motor which after changing the thermostat developed a rough idle.The coil pack and mount was removed to get to the thermostat housing but care was taken not to "ding" anything.Bad luck??? Don't know, but any how. The motor surges at idle and surges very hard when put in gear. Checked the codes and found two codes pointing to the throttle position sensor and O2 sensor, although no service engine light is lit. Tested the throttle position sensor and it tested ok, but i decided to change it out with a new one anyhow. The O2 sensor was also replaced at that time. Still nothing changed so I decided to check the Idle Air Intake valve and it also seemed to test ok ( just checking the resistance reading compared to a new part). So I decided to replace that too just to see what happened, still the same result and the surging at idle is not any better. The car runs ok when driving but at any stop has a very hard time idling. I am not sure what to do now, anyone out there have any suggestions please.?

[KimMG]

Did you check for codes after you replaced the parts? Have you checked for vacuum leaks?

[mightymoose_22]

Assuming all was well before replacing the thermostat....

The main components you would have messed with are the coil pack and wires, and maybe a couple sensor wires.

As for the rough idle, I would triple check that your spark plug wires hav good connections. This engine will run on 3 cylinders but will lack power and idle strangely. The #1 is the usual culprit. Make sure they are secured at the coil pack also. Physically remove them, push the bushing back just slightly so you have a visual of the connection, then push the bushing back over until it locks down.

As for the surging I would recommend somewhat the same thing. Inspect the whole area for any wires you may have left disconnected, or loosely connected. The computer is likely missing a signal from somewhere and is trying to compensate.

[Jonny H.]

All was fine before the Thermostat was replaced.
Yes, I searched for vaccum leaks/pulled hoses and triple checked for any wires that may have been disconnected/left loose on accident and didn't find anything. I have not re-checked the codes and will do that tonight. we are talking about a small area and not much accidental stuff to do(i would think), but i will go back and check all these things again just to make sure.

As for the plug wires there was one that popped loose from the coil pack when i removed it and thinking that may have some thing to do with it I did reseat all the plug wires thinking that maybe something wasn't making a good connection, I will check those again also. Although the car does not lack power at all and drives fine on the road, it will surge idle very hard at a stop when in gear and idle rough when in park.

Thanks for the help, I will get back on the status of what I find in case you guys are interested.

[mightymoose_22]

Well usually the rough idle is due to a vacuum problem. Check the vacuum port on top of the intake. There is an elbow on there that likes to crack on the back side. One of the ports may also have a cap... and those caps like to crack open too.
One other thing to conside is a plugged up PCV.... but I doubt that is the problem.

[Jonny H.]

Turns out I did find a bad vaccum hose, fixed it, and everything is running great. Still have no heat so I have removed most of the lower dash and seems like I am going to have to remove the whole dash to get to the heater core.? I have checked the return side of the heater hose from the heater core and it is not warming up so i suppose the heater core is clogged. Just not sure what the engineer was thinking when he put it in such a tough spot.

Thanks for the great insight, I appreciate the help.

[92Pony]

Originally Posted by Jonny H.

Turns out I did find a bad vaccum hose, fixed it, and everything is running great. Still have no heat so I have removed most of the lower dash and seems like I am going to have to remove the whole dash to get to the heater core.? I have checked the return side of the heater hose from the heater core and it is not warming up so i suppose the heater core is clogged. Just not sure what the engineer was thinking when he put it in such a tough spot.

Thanks for the great insight, I appreciate the help.

Just popping in to commiserate;

I don't know if Ford has the market cornered on the heater core thing, but I think they've tried really hard. I have a Mustang, an Escort, and had a Sable. In each of them, the entire dash has to come out to R&R the heater core. I've heard it said that Ford installs the heater core at the first stop on the assy line, and builds the rest of the car around it.

Good luck with your repair! (And glad you found that vac hose)


Wade

[mightymoose_22]

remove the two hoses from the firewall and see if you can flush anything out of there. If you are creative enough, you can come up with a way to run some cleaners through there and flush it out without doing the entire system.

You just replaced your thermostat... does the car warm up properly? Does the gauge on the dash read correctly? There are other reasons the car may be overcoling and preventing output from the core... mainly bypass around the thermostat at the housing.

Yes, you have to dismantle just about everything to get to the core.

[wtousand]

Usually the heat problem is due to a temporarily clogged heater core. If the output hose is not as hot as the input to touch, then the core is restricting water flow and the fan is sucking all the heat it can out of the meager trickle that is left. The test is done at idle after the motor is warmed up and is quite definate. The outlet goes to the water pump, by the way.

This clog usually happens gradually or sometimes quickly when one tries to flush the system and a lot of scale is loosened. Unfortunately, most flush system kits ask that the provided garden hose fitting be installed in the heater inlet which causes a flow in the same direction as normal which perpetuates the problem. This forward flow, even when plugged, will seem like a lot at garden hose type pressure but really dwindles at low water pump pressure. The heater core acts as a filter to catch every bit of loose scale that it can and plugs up.

The fix is to reverse flush the core with a garden hose and homemade hose connecter. A lot of junk immediately comes out and the core works fine afterwards. Almost all heater cores have at least some plugging and can be improved, even if the heater seems to still work. Core backflush should be SOP for all coolant change-outs. Let us know how you make out.

I am considering a simple home-made experimental fix for the nefarious thermostat housing leak-by also, but my heater seems good enough for now even though my '94 heat gage doesn't read very high. The thermostat I took out was as good or better than the one I put back in, dang it.

[mightymoose_22]

A comment on the housing problem.
Like many others, mine was overcooling for awhile. I had read some people had a hard time finding a new housing, or if they did that it was super expensive.

I was able to go down to NAPA and pick it up for.... I think $60-70. It is not called a housing in most of the computers. It is simply callet a "water outlet". Have the store pull it from the shelf and take a look... you will find it in most stores. I put the new one in and my temp has been fine ever since.

[jeffescortlx]

DO NOT change the heater core.
I wasted a full day because I thought it needed to be replaced to cure my over cooling problem.
But like mightymoose_22 said, it's the housing. It has a thermostat bypass built in, so if it ever over heats a plastic valve melt to allow coolent to bypass the thermostat. You need to replace the thermostat housing.