Analyze my Datalog. . .tell me what's causing this

[Italian LX]

Can anyone tell me what could cause what's happening at ET=122.767?


In addition to the obvious Spark loss and ECT drop, the ECU also goes into OL for
about 45 seconds after the occurance (similar to a start-up condition) which you
can tell by the commanded fuel enrichment at that point.

[86GT]

Are you sure it is not the tweecer just dropping data? If the car is acting funny as you stated, then maybe the TFI module is on its way out.

[Italian LX]

Originally Posted by 86GT

Are you sure it is not the tweecer just dropping data?

I'm positive. The car totally loses ignition usually for about 1 or 2 seconds. I've been chasing this damn issue for about 6 months now.

Originally Posted by 86GT

If the car is acting funny as you stated, then maybe the TFI module is on its way out.

I replaced it shortly after this started happening. Since then, I have tried going back to the stock one, and putting a whole different distributor/TFI module on the car.

I'll try to make a list of what I have already tried while chasing this problem and post it here.

[86GT]

How about the coil itself. Maybe it can no loger handle the short dwell time.

[Italian LX]

Originally Posted by 86GT

How about the coil itself. Maybe it can no loger handle the short dwell time.

I switch to a brand new MSD Blaster coil after the problem showed up last Fall. I also recently borrowed QWKSNKE's Screamin' Demon coil a few weeks ago and the issue still exists.

[86GT]

cap rotor?

I guess Ill wait to see the list of things you tried.

[Italian LX]

For those of you that may not be familiar with my car, here is a run down of the vehicle specs and current engine mods:

1988 Mustang LX (previous 4-cyl automatic car)
5-speed
Stock 302 short block from ’91 GT (approx 278,000 miles)
EEC A9P
TwEECer R/T
TFS TW heads w/ Stage II porting*
E303 cam
TFS Track Heat Intake
1.6 RR*
24# Injectors*
70mm TB
76mm C&L MAF (with 24# sample tube)**
MSD Blaster Coil
Autolite 3924 Spark Plugs***
MAC LT / off-road H-pipe / MAC cat back
255lph
AFPR = 41psi*

* These mods have been added since I first noticed the problem. Previously, I had GT-40 iron heads, 1.7 RR, and 19# injectors, I had the AFPR, but I was running 39psi at the time.

** I had the same C&L MAF when I first noticed the problem but had the 19# tube in it. I will also point out that I ran a stock 70mm MAF out of a ’93 Cobra for about 4 months since the problem started.

*** I was running Autolite 104 spark plugs with the GT-40 heads per my machine shop’s recommendation; now use Autolite 3924 per Trickflow recommendation.

A complete list of all mods currently on the car can be found at this link:
'88 Mustang LX coupe


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This is an intermittent problem that I have been having since sometime around late last summer. It seems to be a total loss of ignition that typically only last about a second, but has often lasted for 2 to 3 seconds. It has also been worse; twice I actually was forced to pull over, cut the car off, and crank it back up. On both occations, I would crank the car back up and drive off with no hint of a problem.

I usually experience it while steady cruising on the interstate (anywhere from 60 – 80mph). I do notice that a lot of times it happens right when I hit a bump on the highway (there’s a lot of construction going on), although it has happened during smooth cruising just as many times.

I’m pretty sure it’s not fuel related. I have a mechanical, cowl-mounted gauge so I know my pressure is staying normal during the events. There is also a strong smell of unburned gas just after the car regains power, which must be the fuel that was dumped in the cylinders while the sparks weren’t igniting.

Although the problem does mostly happen on the interstate, that is not the only time it occurs. I will point out that I drive 50 miles (one way) to work Monday through Friday with 40 miles of that being the I-20 interstate. Therefore, at least 70% of my driving is interstate. I have had the issue happen many times while driving around town. A few times it happened under WOT acceleration and almost put my head to the steering wheel when the ignition dropped out.


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I have already replaced many of the components that would most likely cause this problem and none of them have fixed the issue. Here is a list of parts that have been swapped already – the problem was present during the use of all of them:

Fuel Injectors-
Fall 2004 -- replaced stock 19# injectors with another set of used 19# injectors.
Jan 2005 -- replaced with a set of 24# injectors out of Lee’s ’93 Cobra (they were new replacements with less than 50,000 miles)

Ignition Coil-
Fall 2004 -- replaced brand new MSD Blaster.
Mar 2005 -- tried Lee’s Screamin’ Demon coil off of his Cobra
Mar 2005 –- went back to MSD Blaster

Plug Wires-
Feb 2004 –- installed new Autolite wires
Fall 2004 –- replaced with Ford Motorsport wires
Apr 2005 –- tried a Taylor coil wire from a known running vehicle

TFI Module-
Fall 2004 -- replaced the TFI module with one from a local parts store.
Feb 2005 --tried it with stock module back in.

Distributor-
Mar 2005 –- replaced with stock distributor (with TFI module)

Spark Plugs-
Fall 2004 –- replaced Autolite 104 spark plugs with the same
Mar 2005 –- installed new Autolite 3924 spark plugs when doing head swap

Mass-Air Meter-
Fall 2004 –- changed from 76mm C&L to a stock 70mm Cobra MAF
Mar 2005 –- went back to 76mm C&L; changed sample tube from 19# to 24#

EEC-
March 2005 -- Swapped in an A3M computer from a working vehicle.

TwEECer R/T-
April 2005 -- Swap to a brand new unit; including all new wiring and selector switch.

[Italian LX]

I have always suspected a loose or exposed wire that is either shorting out or causing an open circuit, but have yet to find anything. I have (on many occations) left the car running while probing around the different harnesses under the hood and dash and tugging on wires but only found one thing that may have caused the issue -- I fixed that and the problem still came back.

[86GT]

Have you changed the EEC out? What a bout a loose connection on the TFI to EEC. Look at pin 16, 36, 56. Make sure there is no corision and so forth. I would slao check the shield wire. It is supposed to be grounded.

[QWKSNKE]

yes he also tried the EEC out of my 88 GT