IHADAV8.com - Turbo Buick Tech, and Nonsense
Tech Area => General Buick Tech => Topic started by: larrym on June 13 2016, 01:15:47 AM
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So had the car out testing the new seats got on it a bit when I was cruising back home noticed it was really lean and stumbling coming to a stop symptoms of a large vacuum leak drove home popped the hood and grabbed my stethoscope nothing obvious hmmm did a smoke test still nothing swapped the pcv no change. Compression test 5 at 150 # 5 at 135 that might account for the boost flutter. When you fire it up cold it fat idles good until it gets to temp then lean and rough. Tried another narrow band no change the part that really confused me is that there is very little change in the IAC it's right around 15 TPS is good too. My BLM has climbed from 120 at idle to 129.
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Fuel pressure?
Did you put fuel in recently, like right before this happened?
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Fuel pressure is good pump is new last year
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Hmmm I fuel up but I drove it an hour and a half and it appeared fine I will dump a gallon of methyl hydrate in it see if that smartens it up
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EGR?
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It's blocked no leak I could hear with the stethoscope or carb cleaner
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Vac at idle? Any change?
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Vacuum is at 12 seems low blocked the TB and and smoked it again......... a lot pulled the pcv and the breathers no smoke anywhere.
Checked the slack in the timing chain 8 degrees it's sloppy wonder if it jumped I guess it's time to put it on a stand.
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So it's on a stand I pulled the rockers and smoked it again nothing.... Pressurized the intake it holds pressured it there is no obvious leak it does leak down eventually but it takes a while you would think with the way it was running it had a large leak....
Front cover comes off tonight.
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Well I think I found my problem it appears # 5 exhaust valve is bent or burnt it's not sealing that's why the compression was down on that hole charged the cylinders with compressed air it's spewing out the exhaust rapped the valve a couple times with a hammer no change the heads where machined last years new guides and springs oh well cost of playing I guess.
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Well I pulled the intake look what I found. This cylinder had 150 compression and it did not huff out the breather it leaked less than #5 and the leaky valve so a new set of head gaskets and I'm going to try and lap that valve into submission it looks like it's been leaking a while I would take it back to the shop but I'm starting to lose faith. There is a head shop a couple hours away I have heard good things about.
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Damn the luck
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It's actually kind of lucky no graphite in the pan the next time I hit I would have made a mess
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Well this is disappointing looks like a single angle valve grind. I spent a lot getting these set up and don't really feel like putting another 300 dollars into them.
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My heads are on and double checked the chain with a piston stop. and a degree wheel it's out a degree retarded it's installed 4 degrees advanced so I figure it's 3 degrees advance after it stretches 2.
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so what did you do about the valve?
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Were you cheated on all of the valves?
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Took the head to the machinist he touched up the seat and vacuum tested them set me up with 6 new seals on the exhaust valves as 4 were floating and not on the guides. Charged me an hour no parts he said my back pressure was pushing the seals off....
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I am no mathemagician but that would be some pretty serious (back)pressure to push all the way back up the port, and then up the guide in order to lift the seal, under load. Sounds like crappy fitting parts or setup from the get-go.
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I agree Mike the old ones were the stock Felpro the new ones were steel caps no spring.
The liners in the guides were new and tight when I inspected them either the seals were not installed properly or they were too loose to start.
I pressure tested that cylinder after I torqued the heads sealed up so I'm happy. New chain and equal cylinder pressure I'm looking forward to getting it back in. I suspect my boost flutter will be less if at all once this is done.
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yeah...somethi ng ain't right
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so if it was yours car and you had a choice on cam timing would you run it 2 degrees advanced or 2 degrees retarded. My turbo spools pretty quick and lag is not really an issue.
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A while back two of the locals complained there cars were turds. I mentioned to them to check their cam timing. Since I don't know anything, about a year later they checked...and both cams were retarded. Go figure.
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Lol yes I know guys that don't check they just close their eyes and install the cam.
Most of the time it works out ok but you never know what you are leaving on the table.
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it's probably fine as it is, but, if I had my druthers, I would probably rather be +1 from the cam card on a street car
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My thoughts too thanks for the opinion
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Well now I'm beyond stumped.....
Motor is back in new head gaskets, timing chain, intake gasket, leaky exhaust valve sealed up. It's still lean at idle. Tested all the LS coils 1 is suspect I will swap it tomorrow. Than I guess it's time to try a fuel pump. I smoke tested it again.
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..... It's better but something is still a miss. I pulled the dog house and sealed everything again IAC TB power plate Dblock it still idles rough.
IAC is set at 10 TPS is .47 BLM is much better around 120 where it was before. it's late and I will play with it tomorrow. Got 2 extra plug wires I will swap them out 2 at a time and see if that's the problem my wee brain hurts.
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Tps is on the outside edge of the window. Lower it to make sure it stays in. Pull one injector connector at a time and see if there's a cylinder or two that does not make it worse
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Ok I might have found something? I went to start it when it was cold. Start stall, start stall hmm identical symptom to when I forget to plug in the MAF. I unplug the GENll translator fire it up and away it goes idling like a champ throws a code for low MAF but that's to be expected. Checked all the wiring to the GENll it appears fine. Gonna see if I can borrow a regular translator and a chip to try see if that changes anything.
I reset the IAC 20 and TPS .45 seemed to idle a little better.
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Would not be surprised
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Ok I decided to reset the IAC by tripping the ALDL port and setting my base RPM. I got the rpm down as low as 475 and set it at 525 reset the TPS and fired it up hmm idles good IAC is at 25 TPS is at .43. Shut it down tighten everything up and fire it up goes super lean rpm is low WTF look at the IAC it's at 175 .... So its trying to bring the RPM up but I guess there is not enough fuel there to do it?
Shut it down fire it up and it's fine, try it a half a dozen times and it's good 5 out of 6 but every once in a while The IAC goes mental.
Am I correct in thinking that the fueling is not right on the odd occasion it goes mental or could it be the IAC?
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Larry over the last 4-5 years my IAC will act normal most of the time & then do like yours & read really high & I've swapped/cleaned a couple of them. One thing is my idle stays about the same no matter what it reads so in my case I don't pay much attention to it. If yours is good 5 of 6 times maybe drive it for a while & see how it acts after a couple weeks?
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When it acts up its not really drivable. I am able to watch what is going on in the MAF translator air flow in is typically at 6g on the translator hz in is 1800 hz out is 39 and rpm is around 850 IAC is at 25.
When it loses its mind air flow in is 10-11g hz in is 2100-2200 hz out is 39 rpm is about 700 IAC is 175. Some thing is very a miss.
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The only time my car acted somewhat similar to your kind of erratic readings with some popping & farting was when my stock MAF sensor was having a slow death. Probably not much help for your problem. I hope you get it sorted out because that kind of stuff makes me Nuts! :icon_eyes:
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I'm leaning towards a translator issue
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Did you consider a blocked exhaust. Do you still run a cat? In the old days we used to have double wall pipes separate and crimp the inner wall shut, not on GN's but mostly Chev's. The way your car is behaving reminds me of that, especially with only 12" vacuum.
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It's a 3" single shot and I tested the vacuum again it's up now to18 tested with a different gauge
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So swapped in my buddies translator and TT chip purred like a kitten....
BLM was good IAC was good.
Reinstalled mine and was reattaching it to the dash it dies. My buddy tugs on each wire on the connector and duplicates the symptom twice. Looks like I need the connector repined we tightened them as best we could with a pick but I'm going to get the pin tool and take it apart add new connectors on the plug see if that smartens it up.
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Good find Larry!
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:cheers: :cheers:
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It`s so nice to you find little Gremlins like that before they drive you borderline insane! :rock:
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I'm beyond borderline with this one.
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So I got a regular translator installed tonight borrowed a chip and I'm back. Now I gotta tune it all over again
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What chip?
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It's one of Eric's chips they work good 21-23 for timing I hit with about 18 psi was pig rich I will crank it up a little at a time.
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Eric writes the boost pressure on the inside of the chip. It'll give you something to go on...depending on the turbo it was burnt for.
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I believe it was burnt for 23 psi. It's an alky chip. I actually sold it with a set of 60s to my buddy.so the only real difference is my turbo my new one is BB both were 61a.
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If it's a 5.7 version...bump the low gear timing to 129. It'll go into 'aggressive' mode. Have fun. :)
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I was going to ask that question thanks I'm just glad I figured it out.
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Pretty lucky to have GN northwest just across the border had the translator in 2 days. No way to really data log now back to tuning with a scan tool and gauges. I might have to invest in a power logger.......
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Well got it up to 21 psi afr is at 10.8 if If I add more I will have to add fuel at the same time. Feels good thanks for the tip on first gear timing Brad
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Glad it's running nice Larry. :)
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Pretty lucky to have GN northwest just across the border had the translator in 2 days. No way to really data log now back to tuning with a scan tool and gauges. I might have to invest in a power logger.......
http://www.turbotweak.com/forum/index.php?threads/powerlogger-software-and-installation-docs.1687/ (http://www.turbotweak.com/forum/index.php?threads/powerlogger-software-and-installation-docs.1687/)
Head over here and download the fourth link in the first post. You have to unzip it and install it. Once you do you can open other peoples files. I find it quite nifty.
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it was very rich for 21 psi...you may be surprised at what A/f it runs best
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Glad you got it going Larry!
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Larry. Beg...borrow.. .or steal PL. :rock:
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looks like I got a powerlogger lined up once I have it in my hands I will share some files for the experts to critique I'm pretty excited there is so much more data on the power logger files.
Thanks for the link Rich the software is already on my tablet.
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👍