Xnke Posted July 22, 2012 Share Posted July 22, 2012 (edited) So I pulled a solid-lifter, MN47 cylinder head, camshaft, rockers, lashpads, everything cylinder head/valve cover at the parts yard last weekend. Would have gladly bought the whole Maxima, but they won't sell the whole thing for anything reasonable...the only thing wrong with the entire car was that it had chucked the #2 rocker arm off. Found it, the lashpad, and the mousetrap spring in the head, along with a brand new spark plug, brand new injector, and new wires, cap, rotor, coil, distributor...the PO was chasing a miss that he could have found easy with a new valve cover gasket... Anyway, we used the Timesert 18153 method to convert a running, driving, boosted-to-14lbs-and-loving-it L28et to the solid lifters and the "K" stamp camshaft this weekend. Did NOT unbolt the cylinder head. Pulled the cam towers and those five headbolts to do the job. Removed and replaced all the lifters with the solid adjustment posts, set all the posts at the lowest position possible, and replaced the "K" cam back in the head, in the original P90a's cam towers. Made certain that before bolting the cam down, the cam was rotated into the correct position relative to the crankshaft, then bolted the cam towers back down, replaced and re-torqued the head bolts, and re-fitted the timing chain. All the rocker arms were kept with the respective cam lobes. All the lash pads were checked and the lash pattern verified once the lash was set at .010" intake, and .012" exhaust, cold specification. Everything appeared correct, so we buttoned it all back up and fired up the engine. Congratulations, guys, you just invented the Mexican Three-Cylinder 1.25L, Turbocharged, Fuel Injected, L12-and-a-half-ET. As far as we can tell, nothing out of the ordinary happened. All the valves open and close as they should, the engine has fire and fuel on every cylinder, yet you can pull the plug wires and injector clips for cylinders 2, 3 and 4, and there is absolutely no change in the running engine. The engine is running solely on cylinders 1, 5, and 6, and actually is surprisingly drivable...It'll still make 10lbs of boost! Sounds like hell, though. No, we didn't discover the three-cylinders-down thing before the 10lbs of boost bit. What the hell, guys? The K-stamp camshaft appears to have more lift, but similar duration, to the M-stamp turbo grind, the only difference being that the intake cam lobe is moved four degrees, bringing the lobe seperation angle to 106* instead of 110*. Valve lift is .390", duration best I can measure is 219* at 0.050". (exhaust valve has slightly less duration, 218*. This is within a tight margin for error...so could be the cam is 219/219...which is more likely) This engine should not have had piston-to-valve contact in any way, shape, or fashion, but that is what it's looking like to me. What do you all think? Edited July 22, 2012 by Xnke Quote Link to comment Share on other sites More sharing options...
NewZed Posted July 22, 2012 Share Posted July 22, 2012 A cylinder pressure check would tell you if the valves are damaged and/or opening and closing correctly. Plug wires installed in backward rotation order, maybe, as another possibility. Quote Link to comment Share on other sites More sharing options...
Xnke Posted July 22, 2012 Author Share Posted July 22, 2012 Looks like a valve issue; but I have absolutely no clue how we could have bent valves. The cam was removed and replaced vertically, so I guess we are just stuck with pulling the head to check. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted July 22, 2012 Share Posted July 22, 2012 (edited) Do a compression/leakdown before you pull the head. Check the dumb stuff, firing order, did you accidentally put the cam in 180 out, etc? Edited July 22, 2012 by letitsnow Quote Link to comment Share on other sites More sharing options...
stprasinz Posted July 22, 2012 Share Posted July 22, 2012 If the cam was 180 out, it would still be synced with the 720 of the cam, it would just make the dizzy 180 out... But neither would explain the 3 cylinders doing nothing. compression test! Quote Link to comment Share on other sites More sharing options...
Xnke Posted July 23, 2012 Author Share Posted July 23, 2012 The three cylinders fail everything, including compression testing...but not by very much at all. Looks like time for new valves... Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 23, 2012 Share Posted July 23, 2012 "The three cylinders fail everything, including compression testing...but not by very much at all." Could you PLEASE explain exactly what that means? What I read there tells me absolutely nothing, and is the basis for very poor decisions. Especially if you're working on electronics! Quote Link to comment Share on other sites More sharing options...
z-ya Posted July 23, 2012 Share Posted July 23, 2012 Sounds like bent valves to me. Quote Link to comment Share on other sites More sharing options...
Tony D Posted July 23, 2012 Share Posted July 23, 2012 Bent valves usually mean Zero Compression no? I don't see how a bent valve would "fail everything...but not by very much at all" It's that last part that's throwing me! Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted July 23, 2012 Share Posted July 23, 2012 Yeah, I'm confused as well. Quote Link to comment Share on other sites More sharing options...
z-ya Posted July 23, 2012 Share Posted July 23, 2012 Bent valves usually mean Zero Compression no? I don't see how a bent valve would "fail everything...but not by very much at all" It's that last part that's throwing me! I guess I was interpreting "The three cylinders fail everything, including compression testing..." Quote Link to comment Share on other sites More sharing options...
pallnet Posted July 23, 2012 Share Posted July 23, 2012 Sir Where is the air leaking out during the leak down test? I would be willing to bet that if you have the timing correct and there are no other issues then your HG is not sealing since you pulled the head bolts out to remove the towers. I don't remember off hand. Is the MN47 cam intermaly oiled or externaly oiled? If it's internaly oiled then the cam towers didn't didn't need to be touched, remove the hood, loosen the mounts and lift the motor a little as needed. If you swapped to a spraybar style then yes they would need to be removed but in that case it's best to remove the head. pallnet Quote Link to comment Share on other sites More sharing options...
Xnke Posted July 24, 2012 Author Share Posted July 24, 2012 I mean that cylinders 1, 5, and 6 read 120PSI even, and 2, 3, 4 read 60psi. The valves are definitely leaking; but they are not leaking like "Bent Valves" normally do. Much more like slightly burned valves would behave, which doesn't seem to account for the totally dead nature of the cylinders. Even 60PSI should be enough compression to fire off weak, but they don't. Leaking is coming from #2 intake, #3 intake, and #4 exhaust and intake. The headgasket seems to be sealed up fine...I mean you are to retorque the headbolts on many brands of gaskets, including OEM, by backing them off till they are at zero torque and then re-torquing them, only difference is those are done one-at-a-time. I think when we bent them was the removal of the rocker arms. I told him to be careful and note cylinder position, but I was not present when they were removed so I can't say if that was done or not. We decided it was better to just lift the cam all at once with the hydraulics, but not before we'd actually removed all the rockers normally. Yes, the MN47 head uses an interally oiled camshaft. Quote Link to comment Share on other sites More sharing options...
Xnke Posted July 31, 2012 Author Share Posted July 31, 2012 (edited) Cylinder #3 definitely fails the acetone-in-the-port test, as does cylinder #4...but cylinder #2 so far is sealed. Heck, even 1, 5, and 6 exhaust valves are seeping. I dunno guys, new valves will be fitted up this week and the head will be carefully pressure tested and the cam measured up. Once it goes back on the engine, before it ever gets started up, another compression check will be done. I swear if this thing doesn't run properly after this I'll buy the matches if he buys the kerosene... :fmad: We drove the car 55 miles, with not even a hiccup, before we did the cam swap. On the first startup after buttoning it all up, we were missing three cylinders...and nothing we could do brought them back. Edited July 31, 2012 by Xnke Quote Link to comment Share on other sites More sharing options...
Xnke Posted August 4, 2012 Author Share Posted August 4, 2012 New valves fitted, head pressure tested for cracks. Chambers cleaned and CC'ed, valve seats equalized, all valves lapped after cutting the seats to verify contact area and then vacuum leak tested. After the leak testing, new stock valve stem seals went on. (one of them was off, and seeping oil, as would be expected. No bent valves. All the valves measure out fine, but some of the valve seats, exhaust seats especially, were REALLY funky and pitted. Back on the car. New headgasket, Fel-Pro Permatorque MLS, New intake/exhaust manifold gasket, fel-pro cardboard-type. Filled the coolant and prelubed the cam, set cold valve lash and buttoned up the engine. Cold compression test readings: 112, 113, 112, 113, 113, 113 Start the car, run engine on three cylinders again. No change at all. Unplugged injectors for 2, 3, 4 and no change in idle. Let engine come up to temperature. Hot compression test readings: 120, 120, 120, 120, 120, 120 New spark plugs, NGK 6BP6EY11. Factory recommended plug, according to the plug charts. Standard copper core plugs. No change in engine. Runs on 1, 5, 6 only. Cyls 2, 3, 4 plugs clean white. 1, 6 dark, sooty. 5 white with black stripe down one side of the ceramic. Injectors are new, only been in the engine about 4000 miles. MDL450, 450cc/min, low-Z, "DSM Turbo" injectors. Widely used; these are the black-top version. (New new, not junkyard pulls.) Anything? Anything at all? Quote Link to comment Share on other sites More sharing options...
kiwi303 Posted August 4, 2012 Share Posted August 4, 2012 Doesn't the stock ECU Batch fire the injectors in two clusters? Check the ECU sticky for that, but I suspect the injectors may be getting bad info and not doing the job right on one batch. Borrow a known good ECU and plug that in place of yours and see what happens. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted August 4, 2012 Share Posted August 4, 2012 (edited) At this point it sounds like the cam swap is a red herring. Go back to basics: combustion requires air, fuel and spark. Let's assume you've got air worked out now with the rebuilt head. Spark: it's pretty simple to test if the non-firing cylinders are getting spark - pull the plug wire while it's running and bring it back to the tip of the spark plug. You should see a spark jump the gap. Or you can get a test lamp at a parts store and insert between the plug wire and the plug. Fuel: Like kiwi303, I believe the stock system fires the injectors in 2 batches, although I wouldn't expect them to be 1,5,6 and 2,3,4. With the engine running, take a hose with one end in your ear and bring the other next to each injector. You should be able to hear it clicking. Or you can put a screw driver on the injector and try to feel it. After running for a while, I would expect the non-firing plugs to come out wet from unburned fuel if the problem is due to lack of spark. Those are a few simple things you can do to begin trouble shooting. Edited August 4, 2012 by Zmanco Quote Link to comment Share on other sites More sharing options...
Xnke Posted August 4, 2012 Author Share Posted August 4, 2012 ECU is MS1-extra; injectors are wired such that 1, 2, 3 and 4, 5, 6 are on separate injector drivers. Injection is Simultaneous, 2 squirts. Req. Fuel is 7.0; as calculated by Tunerstudio. Spark is a stock turbo coil; through a new cap and rotor, MSD 8.5mm cut-to-fit wires. I'll check spark again today; but I'm pretty sure I have spark. The injectors seem to be working; they all click appropriately, and best I can tell they are all squirting fuel. More testing to come. This car will run again; I will not be beaten by an L12.5ET. Quote Link to comment Share on other sites More sharing options...
letitsnow Posted August 4, 2012 Share Posted August 4, 2012 I don't mean to restate state the obvious, but you're sure the firing order is right and on the cap in the CCW direction? If it's on in the CW direction, it'll run on 1 and 6, ask me how I know! You're sure the injector clips are making good contact? Check with a test light? Swap the injectors around? I'd also say the cam swap isn't necessarily the issue now. Quote Link to comment Share on other sites More sharing options...
NewZed Posted August 4, 2012 Share Posted August 4, 2012 Since you're injecting simultaneously you could swap injector connections around to check injector vs. spark. Quote Link to comment Share on other sites More sharing options...
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