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1987 Ford Ranger Malfunction - Ignition System
Question: Spark irratic to all plugs, most seem to spark quickly for a most of the time but short pauses in the spark pattern seem evident (using a timing light). One plug is nearly always in the pause mode (no spark) then occassionally a quick burst of sparking will occur which momentarially speeds up the bucking engine. Engine runs smooth with spout connector removed. Ign module replaced about 4 or 5 yrs ago. App 150K miles. I was going to have the Ign tested but Hall sensor?
quick
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Owner: Problem came on quick: on first acceleration noticed missing as revs went up, shifted to 2nd & all seemed ok. Continued to drive but roughness & missing increased - some backfiring. Within 8 miles & 15 mins, it was so bad I could not move the car. Will idle rough so while waiting for a ride opened the throttle & hoped something good would happen - pipes got so hot they started a fire under the truck (much oil under it).
With spout connector in - timing mark is moving around (I asssume as that plug missfires). From what I get get off the internet, could be Ign module, Hall sensor, or Engine control module or spout connector wire shorting to ground - or who knows what else.
Dick
Owner: Cool today - not sure if that is important but testing yesterday was done at higher temps. Today it will not idle with spout connector in place. When removed it will idle, but roughly. Now there is no spark going to the front two plugs on the passenger side (using inductive timing light to make the observations). So either this problem is temp related or something is getting worse (or both) - yesterday with spout connector removed it ran smoothly (so I feel it was sparking @ all plugs).
Technican: Which engine do you have?
Owner: Sorry bout that - 2.9 V6 - it has the TFI-IV ign module I believe.
Technican: I think there was a tech tip to remove the spout connector for running concerns.
These modules were very troublesome. Have you priced a new one? If it has never been replaced before it's highly likely it'll need replacing soon enough. What kind of test were you talking about having done? If this is a test done at your local parts store, I'm not sure how accurate it'd be. Their tests seem to only prove a dead or live sensor, but offer nothing conclusive on an intermittent one.
Owner: It was replaced in 00 or 01. Then there was no spark which is what I have heard from the auto parts store that they usually are dead rather than causing significant sparking issues as I have.
Since this unit has less miles than when the original unit failed (& I thought it was supposed to be more reliable), I have not jumped on it as I might otherwise would have.
Owner: In researching the problem, I found some sites that seemed like they were similar to mine. This one is very simliar - merkurencyclopedia.com/EEC-IV/spout.html.
Since it appears that ign module, hall sensor (PIP), & engine control module could all be potential reasons - thought it best to pay for some professional help. I was hoping for specific direction & testing methods.
Technican: Here is some testing you can do.
autozone.com/servlet/UiBroker?ForwardPage=/az/cds/en_us/0900823d/80/0f/87/c2/0900823d800f87c2.jsp
To accurately identify the problem you'd need a DSO (labscope). Most mechanics don't have one and it's expensive to pay one that does. You could take ohm measurements on the pip sensor while cooled down and visit the autoparts store and compare the reading on yours vs a new one. If the difference is significant you have likely found the problem.
Owner: I have already checked the ign module to the specs on the auto zone site (they were on another site maybe the site I gave you) - mine looks ok. Nothing there on how to check the PIP/Hall sensor - as you said check it against a new one at the store. I appreciate the info but it really hasn't advanced my trouble shooting, I have had to keep going w/o inputs this afternoon to resolve my problem in a timely manner. I think I must now remove the distributor to get at the PIP/Hall sensor.
Technican: I would price a remanufactured distributor before disassembling the one you have to replace the sensor.
Unfortunately, you need a high end scantool or a dso (oscilloscope) to view the sensor waveform to determine if it's bad. In the past when extensive diagnosis is published by the manufacturer, I've taken the alternative route and compared ohm readings with known good componenets to suspect ones and been suscessful (keep in mind the manufacturer does not consider this accurate).
You can learn a great deal about waveforms at aeswave.com. I'm sorry there are not simpler instructions available.
Owner: Progress was not so good - got the distributor out & checked the hall sensor against a new on but saw no real difference. Could not think of anything else that could explain the "worked once with the spout connecter removed & the next day had two plugs not firing in the same situation (spout disconnected)". Purchased the hall sensor & proceeded to break the distributor drive gear when I attempted to pull with a gear puller - rebuilt distributor on order, due here in the AM. Here's How To Get Guaranteed Solutions In Minutes
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