Q on effects of boost leaks

[Sand Storm]

I bought a 93 Ty a few weeks ago with a blown engine. I just finished installing the spare engine I had sitting here a few days ago. The problem I'm having now is the truck makes really no power and has a stumble/miss coming off idle. I went through all of the threads and tried all of the preliminary as well as in depth regarding the usual suspisions (ign., vac. leaks, compression, etc.)and none of them really give me the info. I'm looking for.

When the truck was running I pulled the plug wires off the cap one by one. It seemed like #2 & 4 were dead because nothing seemed to change when those were off. The real strange thing to me was #6 off made thing start backfiring.

The engine has new cap, rotor, plugs and wires. I can't imagine it could be an ignition problem. Especially because it almost seems to get better at higher rpm's.

I thought maybe fuel? Checked the plugs they smelled like gas and looked very normal actually. Checked for pulse w/ a noid light and looked alright.

Now, I know I have major vac. leaks. Especially from the TB shaft and the coupling between the IC and TB. Today I fixed the coupling and It's pretty much down to the TB shaft. When I test the system I can't even get it to go above 15psi and there is NO holding to speak of. By fixing one leak though, things seemed to improve some.

I know what boost leaks do to my Eclipse but I've never experienced this much power loss. But then again, I bought this truck w/ a blown engine so there is no benchmark.

The only code I'm getting is 44 which I understand is O2/lean. This only comes on when the truck is in open loop during warm up. Also, it seems to only be when the idle drops very low like 500-600 rpm. I'm figuring this is all due to the leak.

OK, I know there's some things I'm forgeting to mention but I'm almost at wits end. I'm normally the type to sit back and research and I always get my answer that way but this time it's getting old.

The only other thing I can think of right now is that the IC pump isn't working either. Between a boost leak causing the turbo to work extra hard and no cooling going on at all could really hurt performance.

My main question right now is, could a bad boost/vac. leak hurt performance so much? Even if the truck is making 10-15psi. on the gage? Could this leak cause my off-idle stumble? The stumble seems so consistant that it leads me to believe there is more problems but I've tried everything else.

I'm going to keep going with the leak thing and either figure out what needle bearings I need and fix the TB myself or send it to the guy in texas. In the mean time I'll get the IC pump working and fix all of the other crap the moron who owned this thing before me screwed up.

Thanks in advance for any help guys. BTW, my personality is usually the type to be annoyed by the repetitive "what's wrong w/ my car?" questions. So that would mean I'm annoyed by myself right now. :x

Andy

 

[dgoodhue]

IMO a dead IC pump won't cause an engine 'to make no power'.

A big enough boost leak will make a big difference but the boost gauge (even the stock crappy one) won't get much higher than 1-2psi with a major leak.

It could be a fuel pump, but I would guess that it would atleast make some power when got into boost and then fell flat on it face. I would look into spark and ignition, especially since you mention 6 started back firing when you pulled plug off. Is the timing set properly? Is the distributor in properly, is the spark plugs in proper order?

 

[myclone]

I would look into spark and ignition, especially since you mention 6 started back firing when you pulled plug off. Is the timing set properly? Is the distributor in properly, is the spark plugs in proper order?

Ditto on what he said as pulling a plug wire off and having a backfire means something isnt right.

Check for proper firing order.
Make sure the dist cap is seated correctly (part of the ign wiring harness likes to get under the cap but you cant see it).
Make sure IAC valve is working.


Just out of curiosity is the spare engine you put in a confirmed syty engine or is it just a 4.3 out of another non turbo truck. Stupid question I know but sometimes these type things get sorta overlooked around here.

 

[Sand Storm]

Actually, scrap the IC pump. I just went back out to the shop and jumped the pins on the diagnostic plug and the pump is working. I guess I just figured it wasn't working because the water was so warm. I think that must be because of the boost leak though.

I actually had a bit of and ordeal when I went to start this thing the first time. Long story short, I had the firing order starting on TDC exh. stroke. The only reason why I made such a careless mistake was because the order had been wrote on the cap by the previous owner of the donor engine and I just figured that had to be right considering it ran good before it came from the old truck and I never even had the dist. out of this engine yet. In the process of finding this problem I got a good refresher course in dist. style ignitions (considering I'd been getting pretty used to my usual distributor less style!) During the process I had defiantly found the time to assure the firing order and timing was right and all I guess I can say for the dist. setting is that it was running fine in the last truck. I know what you’re saying though. It really seams like a spark problem but all of the variables have been covered I think and the problem's still here. What would make it backfire on #6 anyways?

You may be on to something with the fuel pump. I really wish I had a laptop to use a scan tool on so I could watch some of this stuff, like timing advance for example. Is there any software I could use on a Palm pilot for these things? How should I go about checking the fuel pump? Just set up my FP gage so I can read it while I'm driving? And no it doesn't really have any kick right at first either. This thing is so gutless right now it actually bogs down a bit between hard shifts.

The most frustrating thing to me right now is that I'm usually a pretty decent mechanic, but now I just jumped into a huge undertaking on a totally new vehicle to me. To top it off, the last owners of both the truck and the donor engine had a cumulative IQ that is the equivalent of a squirrels. So really I feel like I’m kind of shooting in the dark here. Who knows what else could have been wrong that they neglected to tell me.

 

[93ty475]

whatever it is, you seem like you know enough about things to get it going sooner or later...give it a break and work on it tomorrow...it'll let you know when you get it right...do a compression check for the hell of it...that mightl let you know if somethings up with #6 (head or cylinder)...what would make it backfire? maybe some kind of pre or post ignition...could even be a sparkplug i guess...

good luck,

 

[myclone]

Not to beat a dead horse here and you sound like someone who has some sense but did you set initial timing to 0 degrees with the "set timing" connector unplugged? Its the single wire sticking out of the harness under the dash above the passenger side floor board (tan/white is the color I think..its been eons since I looked at it).

 

[Sand Storm]

I appreciate the encouraging words and the help guys. As for the timing, yes I definitely set the timing to zero with the brown wire disconnected. That was done with the assumption that the 0 mark on the plate is the deepest "V" in the plate or otherwise the farthest to the right when looking down from above. I've heard of the balancers slipping and throwing off readings... Maybe I'll look into that on mine.

As for the firing order I went over it 100 times it seems on the first night when I was trying to get it running and I'm sure it's right as long as the firing order is the same as the other 4.3's (165432 right?) I'll look again just to make sure none of them switched on me, lol. I'm 99.9% sure that the cap is on right. I noticed it was a pain to get one of the first times so since then I've always been really careful. I'll double check though.

There seems to be a lot of water coming out the tailpipe too. This is only on a cold engine though. It's like 70-80°F here right now and I don’t think it's the season for condensation. I don’t have any antifreeze in it right now just because I figured I'd be tearing this stupid thing apart long before fall or winter anyways. I'll have to add some antifreeze and see if I get any white smoke I guess. I’ll try a leak-down test on the #2 & 4 cyls. that are the suspects as well. I’m a bit worried now about another cracked block or something. That’s why I had to swap engines in the first place. But this engine came from a running truck!

Myclone you were wondering if the engine is for sure a syty engine and I'm pretty sure it is. I say that because the kid I bought it from had it in a Ty and the only thing was that he said it was rebuilt 12k miles ago. Now the shop that rebuilt it is not what I consider a "high-end" shop so I wanted to be sure this thing was alright so I pulled the oil pan and put a Z28 oil pump in it just in case the shop tried to skimp on the budget. When I pulled the pan I was surprised to see that the thing had 2 bolt mains. For some reason I was always under the impression these had 4's But then some buddies were over later and said "oh yeah, there all 2 bolts." I considered their word good and stitched the thing back up. Later, after the engine was in and comfortable I read here that the SyTy caps should have an "N" cast in them. Well it's to late now and I'm just figuring that the shop did use the original block and all instead of ordering a re-man. 4.3 instead. The only other thing I did to the engine was reset the lash adjustment on the rockers because they seemed quite loose and the thing had a tick to it before it came out of the donor truck. I did do a cold compression test on the engine stand just to get an idea of the engines condition and none were below 145psi. I did the test before I reset the rockers but I'm sure the rockers aren't too tight because I did a compression test on the one of the two suspect cylinders I could get to w/ the 3" DP on there and it checked out fine. Now I really wish I would have just pulled the heads and went through it all so I knew for sure what I have in there but I wanted to save time because this thing is killing my race season for my eclipse (as in that motor is still on the stand in bare block form awaiting re-assembly). Here’s a question. This thing still has a tick to it, although its intermittent, it sounds like a lifter tick. Could a collapsed lifter or two cause enough of a valve timing change to kill two cylinders all together? I’m still curious about the code 44 too. Could that just be from the vac. leak in the TB?

I'm to the point now were I'm figuring my problem is either going to end up being a major oversight or a major issue that has not yet been uncovered.

Wow, I seem to have a tendency to overwrite my post. Huh, sorry. But thanks!

Andy

 

[twinty]

you said you adjusted the lash?....the reason i ask is because of my experience with chevrolet roller rockers, especially used ones, is that they dont bleed down properly once filled with oil, thus opening the valve when you adjust them, instead of pushing the lifter down a bit. I had this problem in my 4.3, a buddies 4.3, a couple of vortec 350's. I know this doesnt sound right but it happens. I adjusted the valves on one 350 half turn down from zero lash and then thing would just windmill and not fire on any cylinders, it did backfire though into the intake. In turn i backed them all off so there was a tiny bit of lash and the thing fired right up. i had to adjust all the valves with the engine running or it would just open the valves, this could be a pain in a sy/ty. This could be where your boost leak is when you check it. The air could be going in an open intake valve and straight out a open exhaust valve.
just my two cents..

 

[93ty475]

the water from the exhaust is more common than i thought...if it goes away when it gets warm then it shouldnt be a big problem...the #2 and #4 suspicion you have may be a headgasket between the two...i have seen that on my own as well as one more 30k syclone a week ago...i guess you wont know until you pull the suspect head...your miss sounds to me like a minor problem...the stumble sounds to me like a bug that can be worked out..could even be as simple as a fuel pressure issue...even if your headgasket was leaking between 2 cylinders, you should still have a shitload of power, just maybe a good miss at idle...you'll find it, just get a scantool on it and keep on plugging along...good luck...

 

[93ty475]

That was done with the assumption that the 0 mark on the plate is the deepest "V" in the plate or otherwise the farthest to the right when looking down from above.

on mine, its the middle V that has a hashmark on it...a line, if you will...mine is not the furthest right V...maybe you could clean the plate up and mark a white line down the side of the balancer and on the correct V of the plate to rule the timing out...correct timing is an absolute must for the ecm to do what it needs to and for your truck to run correctly...

 

[Sand Storm]

Well I'm halfway done swaping to a spare balancer off the original engine. (Had to come in to get some dinner). Before I pulled it apart tonight I double checked the timing and it was indeed right on 0° with the brown wire disconnected. I verified my assumption of the the 0° location later when I got down to the plate and I was right about where I believed it was. I'm just trying everything now (obviously starting with the easiest) I'm wondering if maybe the balancer slipped. I've read about it here before. When I compared the old and the spare there appeared to be at the most maybe a 2° difference when I had the two keyways lined up. The thing that suprised me though was that the bolt pattern for the pulley was the exact opposite from each other. That was with the keyways matched up and the marks sorta lined up. I just credited it to manufacturing variences because I can't see how it could affect anything critical.

We'll see if this helps anything. I'm not getting my hopes up yet though. I think next I go to the lash adjustment. Is twinty the only one who has had his experience? Or was I way off by trying to set my lash on a cold engine that had set on a stand for over a year?

One other question I just thought of. Does it matter with these trucks if the timing is set on a cold engine? I dont get how this could affect base timing but I know on our cars we always warm them up to temp first. Not sure why, just what I've always done...

Andy