Bad vibration at higher rpm

[pinellas50]

Re: Bad vibration at higher rpm

The Walboro pump and Racetronix harness are in. But the problem is still there.

To recap, the motor seems to be cutting up under heavier boost at elevated rpm. It sounds almost like a two step. When it starts cutting up and you get out of the throttle, it seems like it runs rough for a second or so and then smooths back out.

I talked again to my mechanic friend and he still thinks this is fuel related. Like mabey the injectors are shutting down under heavier load/rpm. We kicked around ideas such as a bad Hall Effect switch or ignition module failing under load/higher rpm as the computer uses these in figuring fueling? But testing these things at the times when this truck is acting up seems impossible. He was talking about hooking up a test light wired to the injector harness and the light run out to the cowl so I could see it while driving......watch the light under boost to see if the injectors might be loosing power when it's acting up. I don't see that test going to well.

Oh. When I was changing out the fuel pump I was expecting to find that thing in the fuel line that looks like a brake master cylinder. I don't remember what it is or is for but I kept reading that everyone removes it. I could tell that it was the factory pump that was in the tank. Where is that thing?

Any opinions/ideas on this issue? I'm at a loss now.

 

[Don W.]

Re: Bad vibration at higher rpm

The thing in the fuel tank is a pulse dampener. I don't think you can re-use it anyway with a Walbro. Your problem may be ign as well. Do you have a fuel pressure ga? If so does fuel pressure go up with boost? Pound for pound? What plugs set at what gap?

 

[pinellas50]

Re: Bad vibration at higher rpm

OK. Fuel pulseator. I couldn't find one to eliminate. I was just curious about it.

I don't have a fuel pressure guage.

I have NGK's gapped at .32

Screw it. I'm just going to put a new distributor in there.

This whole time I have been working on the theory that the L35 heads shouldn't be causing any kind of serious tuning issue. Might this theory be flawed? Does the stock O2 sensor give a clue on that one in the datamaster file or is a wide band going to be the only way to know that?

 

[pinellas50]

Re: Bad vibration at higher rpm

And Don, I am taking your hint. I'll just need to save up the money for a fuel pressure guage. Probably a wideband and an Ostrich will follow if my crystal ball is accurate.

I pulled the distributor last night and took a look at it. I could only see down in slightly to the pick up and it looked like it had something on the side of the plastic housing. I couldn't tell if it was just a build up of "stuff" from normal use or if it was something like the plastic slightly melting.

I tried to disassemble it to get a better look and replace the pick up and ign module while I was in there. I could only get the inner shaft to come up so far(yes I pulled the drive gear off) before it siezed in the housing. So I put it back together and traded it in as a core on a new one today.

I'll drop the new distributor in ASAP and post the results of that.

A little voice in the back of my head is getting louder telling me this is probably going to be an issue brought on by the L35 heads not jiving with the stock fueling.

 

[pinellas50]

Re: Bad vibration at higher rpm

Well, that's some more to think about. The plug wires were new with the tune up about 3K miles ago. I looked them over to make sure they didn't tangle with an exhaust manifold and they were fine visually. But yeah, you are right. Just because they look OK doesn't mean they are.

A plugged cat. I never would have thought to go there. Also an idea for me to look at.

Well the wife just fell asleep on the couch so I guess it's time to head to the garage to drop this new distributor and see what happens.

 

[WyoSyclone]

Re: Bad vibration at higher rpm

Sorry I've missed this thread... have been working on some of my own Sy problems

I haven't read about whether you checked the coil or not... definitely something to check. Resistance through the coil lead <5k.

You replaced the pump, did you replace the fuel filter? You're close to maxing out your inj DC towards the top of your run, so your injectors may be trying to compensate for loss of flow by opening up further.

When you replace the heads and had the fuel rails off, is there any way you could have twisted or kinked a fuel line? Kind of a long shot, but had to ask?

Your problem is about as mysterious as mine... I'm getting ready to take mine down to have the CAT looked at.

 

[pinellas50]

Re: Bad vibration at higher rpm

Another new fuel filter went in with the new pump. I checked the entire run of fuel lines and they are OK. Fuel rail as well.

I have not checked the coil. Honestly, the only way I know to check one is to replace it. So all wires should have less than 5K ohms. I'll check to see if my multi meter has that function...I've never done it.

I got the truck up and running last night but it got too late to take it out for testing.

I'll report back on how it does. And how it does at only 8 psi boost if it is still acting up.

Thanks all for the help.

 

[pinellas50]

Re: Bad vibration at higher rpm

OK. Took it for a drive today. As you can imagine the problem is still there.

I pulled the vacuum line on the boost solenoid to limit boost to 8 psi. I got onto a side street and stood on it. The boost guage almost instantly spiked up to 15 lbs and it started sputtering again.............which I tought it shouldn't do with the solenoid line pulled.

Now when I say it runs rough after it does this, I mean it feels like it lost 1 or 2 cylinders. It will run like this for about 1/4 mile or so. I doesn't clear up unless you let off the gas for some time. In neutral it is very smooth.

Plugged cat? Hell I don't know what to think here. And why would it go to 15 psi like that?

Another question. The down pipe is just regular steel right? Not stainless?

 

[pinellas50]

Re: Bad vibration at higher rpm

S****. I thought I wasn't doing something right when I did that. Well, for the split second I hit the throttle it did the same thing that it did in the past.

I'm so frustrated I could scream. I'll pull the ELECTRICAL connection and just drive it. I'm done throwing money at it!

 

[pinellas50]

Re: Bad vibration at higher rpm

OK. Now that I've calmed down a bit.

Did you data log that run? If so I would like to see it.
Did you hear hard detonation? If no, the plugged cat saved your engine!
Did or do you ever get a 'check engine' light? If so, what's the code? (31?)
You say "15 PSI". Is this on the stock gauge, or an after market?

Try it again with the ELECTRICAL connector un-plugged. See if it runs smooth at WOT.

All the hints and things you're un-covering are pointing to the cat converter. I think it's time to take it off, or cut the pipe, and go for a drive.....

The datamaster file is at the beginning of this thread. I haven't done one since. There was no detonation. At least not audible. No check engine light. I pulled codes awhile back and there were none. The stock guage shot up to around 13 actually. I saw it shoot up quickly so I got out of it immediately.

At this point I am afraid to do this anymore. Once I can scrape up enough money for things like wide band and fuel pressure guages I might get back to it.

EDIT: Sorry DaveP. Had a little temper tantrum there. I'll try to get around to taking the cat off and see what that does. It might take a little time for that to happen though. In the mean time, I'm only going to drive this thing if I absolutely have to.

 

[pinellas50]

Re: Bad vibration at higher rpm

I took it out today with the electric pulled from the boost solenoid. It still has the sputter up near the top end but it isn't as pronounced.

But the thing I noticed is that the motor seems to be down on power all the way across the board now. There feels like very little difference between 1/4 throttle and 1/2 throttle. This is the first time that I noticed it and it seemed to get a little worse as I drove.

The motor is smooth at idle in gear and when reving in neutral. I don't think this is something like a cylinder problem because even when it is down on power it is still smooth. Not imbalanced like when a cylinder goes cold. And there are no noises coming from it other than the sound of the injectors ticking.

This plugged converter is starting to really make sense now.

I explained the issues I was having with it to the wife last night and how frustrated I was with it. She was understanding and hopefully she won't be on my back about this not running right.....again. That should help stop my frustration from pouring out into the thread again. :roll:

So, my plan is three fold. I am going to swap in the good stock turbo I have(mine now has two bent intake fins), and while I have that all apart I will have my buddy weld in an O2 bung into the downpipe for a wide band and probably just replace the converter. I won't be able to do all this till at least next month so I'll check back then.

Thanks for everyone for their help so far.

 

[twin74s]

Re: Bad vibration at higher rpm

Why dont you unbolt the cat and go drive it?

 

[midnightbluS10]

Re: Bad vibration at higher rpm

Why dont you unbolt the cat and go drive it?

x2

It can't hurt anything.

 

[pinellas50]

Re: Bad vibration at higher rpm

I started in on that last night.

The biggest problem I ran into was one of the 2 bolts that holds the rear side of the exhaust to the cat was so rusted that it snapped in half. So the other half is still rusted into the plate thing on the converter.

Aside from that, I didn't see a way to get the cat out of there without pulling the down pipe which I don't want to cut.

Unless someone knows of a way to pull this thing leaving the down pipe bolted up? It didn't look do-able to me last night.

EDIT: I just stuck my head and hands up in there a little more. I guess there isn't some kind of attachment point for the cat on the engine side. I'm going to try and pry the muffler/pipes over some to see if I have enough room to slide the cat backwards off the down pipe. After I unbolt the rubber mount things from the cross member.

Further bulletins as events warrant.

 

[pinellas50]

Re: Bad vibration at higher rpm

Yeah, I screwed with it for about an hour and a half last night. I was able to get the muffler free of the cat. But I couldn't get the muffler to move back far enough to get the cat to slide all the way off of the downpipe. Yes, I unbolted the rubber mounts. I unbolted the down pipe but still didn't get enough wiggle room.

I don't see anyway to do this without pulling the turbo to get enough room to move the down pipe forward and out of the cat. Then I'll be golden. So I'll stick to my plan. At this point, all I have left is pulling the turbo out of there.

The thing that will draw this out the longest is waiting on my friend to get over to my house with his Mig. I think this is an ideal time to have another O2 bung welded in. I'll just get one from an exhaust shop near me and cap it until I can afford a wide band.

 

[pinellas50]

Re: Bad vibration at higher rpm

The new cat is in but the problem still persists.

I guess the next step is getting a wide band and fuel pressure guage. That's going to be some time down the road.

Oh well, thanks for everyone's help.

 

[pinellas50]

Re: Bad vibration at higher rpm

The entire core was still present and accounted for. I don't know if there was something going on in the core but no pieces of it went anywhere. I did not drive it with the cat removed.

I was reading through the syty supplement last night to see if that might shed some light. I did read about testing the exhaust system for restriction by testing the amount of vacuum present. Thesting it at idle and then at 2500 rpm to measure the difference in vacuum its pulling. Has anyone had success with this method? And at this point, the only other thing in there is the muffler. I've never heard of a clogged muffler but I guess that doesn't mean it isn't possible. The muffler is old and it sounds like the jostling around I did with it when doing the cat opened up a leak in it.

The other thing I saw several times was the coil. Would a coil cause something like this? I'm used to Ford stuff that usually works or doesn't work. No in between,


Along the lines of fuel. With the new pump and filter in there now the only other thing could be a tune right? If the FP regulator blew it would be flooding the motor right? Provided that all the sensors are working correctly. They seemed to all be doing something based upon the datamaster files I looked at.

Or does it make more sense to get the wide band and FP guage before anything else here?

 

[pinellas50]

Re: Bad vibration at higher rpm

I pulled the computer down today. The computer box itself still has all the factory tape/cover on the back with PAS warranty void warnings on it. The tape/cover is not tampered with in any way so this leads me to believe that it has to still have the stock chip in it.

I tested the coil using one thread I found here. As far as I can tell it tested out OK. The test measured resistance between several different terminals and later the main plug terminal.

I looked for loose gounds or ones that I might have missed during the head install. The ones on the front of the intake were fine. I couldn't see the ones on the back of the driver's side head. I tried reacing my hand down there to at least try and feel around and ended up getting my hand stuck for several minutes between the firewall and everything else :rant: . I didn't see any loose wires with a little mirror I put back there.......for what that is worth.

Like I said, I plan on getting a wide band and a FP guage. Is there anything anyone thinks I should try before this. Cut the muffler off? I found more about that vacuum test pertaining to the exhaust and read that it wasn't effective. I read during more searching about people talking about drilling holes in things(mainly the cat) to test them.

Right now I am still completely at a loss if I am chasing a fuel or ignition issue. My thoughts are that a wide band would answer that very quickly.

 

[pinellas50]

Re: Bad vibration at higher rpm

I unbolted the muffler and was able to tie it up out of the way. Then I took the truck for a drive. This didn't effect the problem. It is still there. So the exhaust system is now ruled out.

To recap: Earlier this year I blew a head gasket(Felpros). I put in a set of Victor gaskets and put on a fresh set of L35 heads. Everything else is stock. I drove it for awhile after this always babying it. I even took it on a several hour highway trip during this time. In the back of my head I was concerned that those heads might pose a problem. I got datamaster and then started standing on it a little more to see how things were doing. That's when I realized this problem. It didn't do this prior to the head gasket job.

What it does now is sputters at higher rpm, mabey 3K and up, with boost that is normally over say 6 psi. When it starts this sputtering/shuddering I immediately get off the throttle. After it does this, the motor feels like it is running on 5 cylinders as long as any kind of throttle is applied such as trying to maintain the speed you are at or even less. It's very rythmic....chug chug chug chug. BUT after you let off the throttle completely and let the rpms come down it clears up and runs fine. It always has a nice, smooth idle...for a Ty. It isn't using or blowing any coolant or oil.

I have replaced the distributor, fuel pump, fuel filter, and catalytic convertor. The rest of the ignition has about 2K miles on them. The coil is the one that was in the truck when I got it. I did the bike tube test and there are no vacuum leaks.

So what's the next step. Get the guages? Anything else I can try/test? Can anyone think of anything that I might have screwed up putting the heads back on?

 

[pinellas50]

Re: Bad vibration at higher rpm

Dear diary:

Today I went though and made sure that all of the plug wires were tight on the plugs and the cap. They were.

Then I went through and confirmed that all of the vacuum hoses are attached to the right places. They were.

My logic is telling me that this is a fuel issue. If it were ignition, why would the motor be "chugging" just after the sputtering event under throttle? But why a fueling issue? It has a new pump and fuel filter. The fuel lines all look fine and besides, there is nothing that I could have done to mess them up during the head swap. A sensor messing around? Which one and why doesn't it show up on the datamaster pulls?

Oh, I looked at a lot of parts stores to get a fuel pressure tester. They were all $50 and I can only test static pressure with it. I think that $50 would be put to better use going towards an electric Autometer guage in the guage pod I just bought. Mabey I can borrow a static FP tester from my mechanic buddy.

Diary, I think my last shot at figuring this out is getting that FP guage and the wideband. At this point, I'm just making random, slightly educated guesses.