IP Encoder Sensor Replacement?

[ol9465er]

I have an IP question.

My 94 Chev 6.5 has 180K Miles, 70K of which are on a second IP. The new IP is a DS4 2155 so it is of a newer design. I replaced my PMD with A Sol-D FSD about 5K miles ago, and it is working fine, I don't have any problems starting or running, however I am now getting DTC's 35 & 36
when the engine is up to normal running temp (it does not do it when cold) and a steady SES light.

A long-time, reputable local Fuel Injection shop says that this is symptomatic of a faulty "Encoder Sensor" which is the electronics part on the top of the pump. They advise this part can be replaced for about $300 (as opposed to a $1200 IP - all my install labour to take out and re-install the IP of course) but they say that the IP must come off and the Encoder Sensor be replace at the shop so that it can be calibrated otherwise my fuel mileage could end up very poor.

Another mechanic however, told me that I could replace this at home without removing the IP from the truck.

Has anyone had experience with replacing the Encoder Sensor, and if so, can you offer advice. What calibration is require and how can it be performed.

Any help appreciated.

Thanks,

ol9465er
1994 Chev 6.5TD, LWB 4X4
Stock except for SOL-D

[DChristie]

Codes 35 36; ignition pulse width fault.

I would start by looking for loose connections or an intermittent ground problem someplace else before I'd spend the time and money (especially the money) on a new sensor. It has not been my experience with encoders that they cycle before they fail; they are good or they are not. and they are fairly robust, barring sending 120v to a 5v sensor, :rolleyes: they survive most things.
I have no idea what the parts-house cost is, but a few years ago I encoded a machine for the inspection company I worked at. The encoder I used cost about 35.00, multiply that by 10 because of an automotive application, submerged in diesel, and somewhere between those two numbers I'd bet lies your cost.

It has been a while since I did it but I bought a dead IP on ebay to take apart. It could be done in the truck, fairly easily. The lid on the IP is held on by 6 torques screws. Once the lid is off, you are working at a bench... and the sensor is held in place through the lid by a big snap-ring.

Hope this helps.

DChristie

[CareyWeber]

Here is a link to encoder replacement.

http://www.mamut.com/homepages/Norway/3/4/royh/newsdet9.htm

I would not do the encoder till I'd checked every electrical connector.

Carey

[ol9465er]

DChristie / Carey...

Thanks for the posts.

I have checked all the connectors, ground etc.. I was getting several other codes previously and found the engine to firewall ground loose. Cleaned and tighten all a month ago and have been working fine until this. Have re & re'd all connectors since but still the same. I seem to be down to the last straw. The dieseltech told me to unplug the encoder sensor and start the truck and see what happens. He said should run rough but run - going to try this tomorrow. Don't know what to do next except the sensor or the pump?

ol9465er

[tom.mcinerney]

Assuming you've gone over all battery cabling & grounds, and inspected/cleaned most harness connections (maybe tempted to reseat PCM connector), good luck.
The highest standards of cleanliness are expected for FIP work.
Handle the sensor with care.

[ol9465er]

Tom Mac...

Thanks, have done all connections including PCM. I keep my engine compartment very clean and painted so not too concerned there.

However the issue is now about the calibration (as mentioned by the mechanic). Anyone know what is required in terms of this. Are there special bench tools required. I might have to take it off an leave it to them if that is the case.

Thanks all.

ol9465er...

[tom.mcinerney]

ol9465er --
I don't know how the FIP works, specifically--mine is working, and i haven't studied GMCTD's threads about the various timing aspects yet.

as a tech i replaced a newly-installed optical sensor in a device once. [i had installed it too]
The engineer who delivered it before its replacement had tossed it, un-sheathed onto a counter. The noise it made landing , and troubleshooting procedure directed me to test it ... a scope indicated its output pulses were not properly phased/oriented , so the circuit couldn't read it.

The photos shown in the link Carey provided mention a scribe line. If you can follow that, you may as well try it. I strongly suggest phoning some of the TDP advertisers/vendors [fuel injection distributors/rebuilders] and asking them for advice. I found the folks at Gomer's/US Diesel very helpful.

Installing a new pump might be better, but if you can get away with an on-vehicle component replacement , you might get double the service from your pump. That might allow you the luxury of planning and installing gears simultaneously. Don't proceed unless you can insure cleanliness. {My pump ate a fair bit of trash thru a compromised filter, and still runs}.

And you can always put in a new pump if the sensor swap doesn't suffice--the new FIP install becomes plan 'B'.

My understanding is the FIP needs a tech with a $2000 scanner for a proper setup. But the pump can be installed at home , and driven to a shop for its proper setup/timing/offset, etc.