93ATX Hesitates/Stumbles

[jebooker]

Hi...My car has been acting up for about a month now...Mainly after it warms up. It is hesitating on acceleration, and idiling rough. It almost seems as if two cylinders drop out evry once in awhile. It will idle @ 800 rpm then for no apparent reason drop to 500 and be very rough until I tap the pedal then it will "come back" to normal smooth idle. I changed to another known good coil, and this had no effect(I got a 217 code on the KOEO test). When driving at HWY speed the tach will bounce, the car will stammer, even when at WOT. Here are the codes I just pulled after clearing, then driving approx 15 mi. KOEO....217/327/332
KOER....412/327/411/538.

Last year I replaced the following....Plugs(Ford), Wires(Taylor), All seals/gaskets on the valve covers, intake gasket.

Thanks in advance for the help....

 

[SHO#7]

Welcome to the forum.

Here is what I gater from your results.

217 - Primary Circuit Failure ( Ignition coil #3 )
327 - EGR Flow Problem
411 - Idle control problem ( associated with high idle )
412 - Idle control problem ( associated with low idle )
538 - You did not goose the throttle during the running test.

You ( I assume ) replaced the coil pack due to the code of 217. Here is my question, when you say that the tach bounces around when on the highway, what do you mean from this. You are driving along at 2500 and it starts to fall to zero. Does it have any running effect on the car when this happens?

I would starte with cleaning out the " egr nostrils " that are in the throttle body. If you search the forum you will find how to do this. I want to think that your uneasy idle is either related to, too much exhaust gas getting to an engine at idle, making it unable to accomidate the poor air quality at a low idle. I also think that you may have a cam sensor failing based on the tach description. IIRC the cam sensor commands spark, where and when etc... If it is not reading correctly, it may not send spark at the correct time. Resulting in the running issues.

There are some more experienced on the board that may have run into issues like yours, and may be of more assistance. Hope you get it sorted out. And let us know about the tach issue. A tach that does not read correctly, is a big symptom of a cam sensor. They are a cheap and easy fix.

Mike

 

[jebooker]

As the tach "bounces" the engine RPM is also noticeably affected, or vice versa. The tach is accurately reflecting the engines performance.

When you say "nostrils" do you mean, the two sets just inside the intake plenum? If so, I have cleaned them recently.

 

[V6&V8SHO]

I had a rough running issue when warm like that on my 93. I replaced the IAB. And my O2 sensors. Later down the road I had a wierd tach/tranny issue that was ground related.

 

[jebooker]

I "sanitized" the IAB when I had the top end apart for the valve cover seals. I also replaced the O2's around the same time. Im starting to lean toward the EGR system...any thoughts??

 

[jebooker]

Could this be DIS related? Also...I did replace computer with the D4u1, but the problem occured after 3mos of flawless driving on it.

 

[jebooker]

What sensor/part(s)affected by engine temp, could cause this...ambient air temp is not a factor. This morning it was 8 degrees, and it ran like a throughobred with absolutely no problem throughout, regardless of the RPM/Speed/Throttle position...for about the first 4 mi/5min. When the coolant temp guage reached the lower mark, then the first stop light, it started the low/rough/missing idle around 400 RPM. Any thoughts along the line of something "warming up" then either staying "closed", or staying "open".