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Thanks for the tip. Now that I know a better way...
Anyway, tried listening to fuel pump with stethoscope and I hear no sound - in ON position or when cranking. I guess I need to open it up and check the 12v.
Now just wondering and looking ahead, how do you check the secondary chip in the LH?
There is no direct test for the LH. If you have a running S4 simply take the LH unit from the car that will not start and hook it up to the running S4. If it no longer runs then you know the LH unit is faulty. First thing however is to put 12 volts across the pump terminals. As I recall the negative terminal is gounded so you just need to connect the positive terminal of the battery to the pump positive terminal and it should spin up.
Just saying, since no one else has,.....
Are you sure your fuel gauge is accurate?
Only asking because on my 83 ROW, I thought I had a major problem a couple of years ago, gauge showed some fuel, but....
once I added a couple of gallons of gas, I found I had no problem.
Billu, you are so smart. It's maybe a long shot, but definitely worth asking. I've had a car that did the same thing, because the float was stuck and wouldn't go below 1/4 full.
Good luck,
Dave
Just saying, since no one else has,.....
Are you sure your fuel gauge is accurate?
Only asking because on my 83 ROW, I thought I had a major problem a couple of years ago, gauge showed some fuel, but....
once I added a couple of gallons of gas, I found I had no problem.
Yes that entered my mind so I put in 2 gallons in there and the needle went up. So I think I m good with fuel. Thanks for your input!
Regarding the LH. Where are you located? (USA, Europe, etc...). Most people send them to Louis Ott in the USA or John Speake in the UK to test, repair if needed. But you have a running S4 donor car so you could just swap the LH / EZK from that in to this car.
Its possible to track down some new cause for the fuel pump failing to energize, but since you confirmed that it was working just prior to installing the second harness it is likely something related to that, the harness or it’s installation.
Also, since the Porsche mechanic left a jumper wire in your CE panel, you have one of those already to test your fuel pump by jumping it (bridging it). Please don’t open the fuel hose in the engine bay while it’s bridged though. Just try it to confirm that the pump energizes.
IT FINALLY STARTED AND RAN! I swapped the LH/ezk with my other running s4 I have as you and FredR suggested and it worked!
Now I need to get the non working one repaired. I'm in California, USA BTW.
However after it started after about 1 minute some smoke came out somewhere in the driver side firewall.
So I turned it off and will investigate later. Maybe just a piece of cotton rag in there hopefully.
But thanks again for your help and everyone here!
I appreciate it.
The good news - it will now be repaired and won't fail on you at a most inconvenient time.
There's a used one right now on eBay for $370. It's the EZK only. What's the LH by the way? Isn't that the other module?
Should I just buy that one or spend the $500 to repair? Please advise. Thanks!
P.S. Should I replaced the LH or the EZK or both?
Did you swap both your ECUs into your running S4? If so, you need to figure out which one specifically is the problem. Chances are it's the LH, not the EZK module that has failed.
I'm far from an expert, but my understanding is the LH has a board that will fail at some point, it's just a matter of when not if. The replacement Louie puts in has been shown to be as good as new and comes with a 2 yr warranty. He's also very customer-centric and is very good at answering questions. I sent him mine on Wed and had my repaired module back by the following Wed. Most of that was mailing to & from Neb - AZ. He did his work in 1 day. YMMV.
If your LH has failed, no need to replace the EZK. If it's just the EZK, the one on ebay should be fine (others can definitively comment). But your LH will still be a ticking time bomb. Yes, you have 2 S4s and it may not be an emergency to repair a blown LH, but that's assuming it fails when you're home. That's probably a 50-50 proposition.
Did you swap both your ECUs into your running S4? If so, you need to figure out which one specifically is the problem. Chances are it's the LH, not the EZK module that has failed.
I'm far from an expert, but my understanding is the LH has a board that will fail at some point, it's just a matter of when not if. The replacement Louie puts in has been shown to be as good as new and comes with a 2 yr warranty. He's also very customer-centric and is very good at answering questions. I sent him mine on Wed and had my repaired module back by the following Wed. Most of that was mailing to & from Neb - AZ. He did his work in 1 day. YMMV.
If your LH has failed, no need to replace the EZK. If it's just the EZK, the one on ebay should be fine (others can definitively comment). But your LH will still be a ticking time bomb. Yes, you have 2 S4s and it may not be an emergency to repair a blown LH, but that's assuming it fails when you're home. That's probably a 50-50 proposition.
I swapped both. Alright sounds like a plan. Thanks for the valuable advise. I appreciate it!
By the way, it just occurred to me that maybe the mechanic at the Porsche dealership messed up my LH by inserting that bridge at the LH relay socket. But I have no way of proving that. All I know is my LH was working when I brought my car there and suddenly it wasn't working when I got it back . Hmmm.
I don't want to cast aspersions, but hot wiring the LH relay may not be a good thing. It would be sending a constant current to the LH, which may not be good for it. Once again, I'm not an expert so don't hold me to that, but it makes sense.
What's the LH by the way? Isn't that the other module?
Should I just buy that one or spend the $500 to repair? Please advise. Thanks!
P.S. Should I replaced the LH or the EZK or both?
Think of the LH as the car's brain / computer; it has an internal component that eventually fails. The EZK is controlled by the LH, if I understand the system correctly; most EZK's are bulletproof and never fail, but never say never, I had one that did fail.
Bridging the LH relay should be fine, there is no way to tell if your mechanic doing that caused a problem, or not, with your LH or EZK. Did you put the old LH / EZK in to the donor car, just to test them? I know it's counterintuitive but it's just something I would be curious about before sending them off to be repaired since you have a donor car right there.
You don't want to buy a "good used" electrical part off of eBay, that's a crap shoot as to whether or not they actually work, and doing so can just drag out the process of resolving problems. Louis Ott is your go to for LH needs.
Anyway, seeing her fire up (no pun intended) must have been very satisfying! Congratulations!
I swapped both. Alright sounds like a plan. Thanks for the valuable advise. I appreciate it!
By the way, it just occurred to me that maybe the mechanic at the Porsche dealership messed up my LH by inserting that bridge at the LH relay socket. But I have no way of proving that. All I know is my LH was working when I brought my car there and suddenly it wasn't working when I got it back . Hmmm.
The LH has failed- probably just a random thing but...? The LH is a bit unusual in that the firing sequence starts with a signal from the CPS to the EZK and then the EZK sends a signal to the LH and the LH then instructs the secondary board to activate and that sends a trigger signal to the fuel pump relay to energise that [or so I understand]. The device in the LH is a secondary circuit board and that is the weak link of the LH. When John Speake rebuilds the LH he installs a new improved secondary board of his design plus whatever else he happens to do to them routinely. Louie is his US based agent- both great resources. Get a rebuilt unit from that supply line and you get a whole lot of support with it. You also have the option of having your own original unit refurbed and sent back to you but that obviously takes longer. John also refurbs MAF's and of course he designed and built the Sharktuner kits. Just yesterday I had a hesitation/stumble starting and suspected I might have a tem 2 sensor issue- hooked up my ST2 kit, fired the car up and the temp 2 channel reading were both 33C on a cold car- however the ambient temperature yesterday was 33C so that was spot on. Whilst in there I did some adjustments on my idle and that smoothed out noticeably. Those without ST2 simply do no know what they are missing out on.
The LH was the one thats broken. I put it on the donor car. Now I will have to send it to Louie.
Yes I'm happy and relieved that my car is back after being inactive since it caught fire 18 months ago. I thought it was a goner and didn do much until this shelter-in-place happened. 👍
Couldn't have done it without you guys who unselfishly provide a wealth of information.
Thanks Shark2626, FredR and the rest of you guys who posted to my inquiry. I truly appreciate it.
04-11-2020, 05:58 PM
