Strange misfire, HELP ASAP - Page 2

Budfreak · #16 03-20-2007, 09:46 AM

Quote:

Originally Posted by Nomake Wan

Probably totally off-base on this one... but has the ECU been reset since you swapped motors? Maybe it's just not reading one of the sensors correctly...

The battery was disconnected while doing the swap plus I reset it 3 or 4 more times after that and even tried another ECU .

TomsSVX · #17 03-20-2007, 11:40 AM

i have a feeling this may be an effect of E85 on our fuel systems or something like it. It would seem that the return line is clogged and not allowing sufficient pressure to return to the tank... Thus, cranking up the pressure on the in-bound line... Keep at it and let us know, I do not believe this is electrical, probobly mechanical hence the reason for not having any codes.

Tom

Budfreak · #18 03-20-2007, 11:47 AM

Quote:

Originally Posted by TomsSVX

i have a feeling this may be an effect of E85 on our fuel systems or something like it. It would seem that the return line is clogged and not allowing sufficient pressure to return to the tank... Thus, cranking up the pressure on the in-bound line... Keep at it and let us know, I do not believe this is electrical, probobly mechanical hence the reason for not having any codes.

Tom

But if the return line is clogged, Where?? I took the 60 PSI reading directly off the metal return line at the motor and the lines in the rear have been rerun with rubber due to corrosion I'd imagine. I'm taking the car back to her today and they are going to put it on diagnostics and see what comes up. I'm hoping they figure it out, But if not I guess I'll get back to working it out when she returns from vacation.

TomsSVX · #19 03-20-2007, 12:03 PM

by constricting the return line, there is a boost in outgoing pressure. That is the premise in which our FPR work. If there is a restriction to pressure and flow going into the tank (further back than you monitored) then it will still over pressurize the system. You need to monitor the fuel pressure at both the engine and at the tank and see if there is a difference

Tom

Trevor · #20 03-20-2007, 03:07 PM

Quote:

Originally Posted by Budfreak

Yes, I thought of that also, But didn't have the time or energy to swap the coil packs and the miss isn't consistent long enough to trace. I always appreciate your advice Trevor, Your a smart man and a great value to this community. I'm taking the car back to her today and she has a friend who can hook it up to diagnostics and find the exact problem possibly and then I can go right to it and fix it. It also decided to start a small leak yeterday out of the brand new rear main seal, Just as a little bonus for me I guess.

The second I find a select monitor consider it sold. What a value it would have been on this one.

You are taking the best route. In the past I have often pressed on, not accepting defeat in the face of a challenge. This is/was stupid and not a commercially viable attitude.

Budfreak · #21 03-20-2007, 10:06 PM

Quote:

Originally Posted by TomsSVX

by constricting the return line, there is a boost in outgoing pressure. That is the premise in which our FPR work. If there is a restriction to pressure and flow going into the tank (further back than you monitored) then it will still over pressurize the system. You need to monitor the fuel pressure at both the engine and at the tank and see if there is a difference

Tom

Well I already checked at the engine on the return line and it was at between 60-64 PSI.

How could it be so high coming directly from the running engine with the regulator plugged in? That wouldn't have anything to do with the return line being clogged as it is unhooked from the engine and the pressure tester is hooked to it just inches or so from the regulator, therefore no return flow to the tank to cause the pressure. Or am I misunderstanding you?? I am going to check the pressure at the tank this week and see what's going on there though.

Budfreak · #22 03-20-2007, 10:17 PM

Quote:

Originally Posted by Trevor

You are taking the best route. In the past I have often pressed on, not accepting defeat in the face of a challenge. This is/was stupid and not a commercially viable attitude.

Agreed. I just hope I find one soon.

TomsSVX · #23 03-20-2007, 10:30 PM

there lies your problem... The SVX has a free flowing fuel system.. Meaning all the gas pumped in, if not used is then allowed to flow back to the tank... If you are intereupting the flow back to the tank, this is when the pressure will rise. You need a t connection and tap into the fuel system that way to test the pressure

Tom

Budfreak · #24 03-20-2007, 10:33 PM

Quote:

Originally Posted by TomsSVX

there lies your problem... The SVX has a free flowing fuel system.. Meaning all the gas pumped in, if not used is then allowed to flow back to the tank... If you are intereupting the flow back to the tank, this is when the pressure will rise. You need a t connection and tap into the fuel system that way to test the pressure

Tom

Aw yes, I see. Ok, not a problem. I'll check it out this week and see whats happening.

Thanks tom.

SURTEESS · #25 03-21-2007, 03:10 PM

Had similar issue with mine, ended up being a faulty spark plug lead. When the leads where taken out to replace spark plugs.

Upon pushing the spark plug leads into the other various connectors - 2 of the leads worked fine when cold, but when warm/hot the lead contacts became open circuit, causing misfire & "hunting" revs (rev bounce & no speed increase due to misfire).

What I noticed was that when lead was mated the pins sometimes get pushed out from rear of the plastic connector body - this was easily sorted by pushing pins as far forward with a small screwdriver & re-potting with a hi-temp silicon glue from the back of the connector body.

It only took me 2 hours to find the problem!!!.

Have fun

Steve in New Zealand

Trevor · #26 03-21-2007, 05:00 PM

Quote:

Originally Posted by Budfreak

Aw yes, I see. Ok, not a problem. I'll check it out this week and see whats happening.

Thanks tom.

In this connection your mention of the following has come to mind. :-

"the lines in the rear have been rerun with rubber due to corrosion I'd imagine."

This is a practical issue and could involve/inicate a possible fault caused by others. Well worth careful scrutiny.

All hands to the pumps.

But you have the donkey work.

Budfreak · #27 03-23-2007, 10:41 PM

Today I checked the fuel pressure(perfect 36 lbs. with regulator unhooked) and engine vacuum(19 inches steady at idle).I also disconnect the 4 main engine harness plugs and cleaned them with electronics cleaner and I also cleaned the MAF plug and the TPS plug. I also tried resetting the ECU when all was done. All to no avail still.

I'm wondering about a wire that has been severed and spliced at the ECU and now runs to one of the relays in front of the panel the ECU mounts too. It's on the far right big connector on the ECU and it is I believe the 3rd or 4th wire from the right in the front row of wires in the connector and it is orange. Any other ideas?? I guess I'll resort to coils next as it is one of the last things I haven't done yet.

Any other ideas?

TomsSVX · #28 03-23-2007, 10:43 PM

probobly a weak coil then... I need to do coils and plugs in my car anyway. Let me know what you find

tom

Budfreak · #29 03-23-2007, 10:44 PM

Quote:

Originally Posted by TomsSVX

probobly a weak coil then... I need to do coils and plugs in my car anyway. Let me know what you find

tom

Will do.

TomsSVX · #30 03-25-2007, 07:19 PM

Well, I had some extra time today and I went ahead and replaced all 6 of my coils with ones I know to be good(from a previous motor). My issue is fixed... thank god because I cannot handle the 10-13mpg I was getting for the past 3 months

tom