Another no start for 92 3.1

Trying to figure out if she jumped timing or maybe PCM went out. Car started dying going up hills then stalled out on level road. Found coil pack for #3 and #6 bad and replaced it. Other's arced ok so I left them alone. Didn't help starting it so I checked the fuel pressure and got 37psi with key on and engine off. Any idea's about what would cause it not to even try to hit? Considering maybe it's jumped timing or the PCM is going out. Thanks in advance for any idea's.

Since the fuel pressure seems adequate, is fuel getting to the cylinders? If you manually apply fuel or a little starting fluid, does the engine fire?

If administering fuel or starting fluid produces results, are the INJ1 and INJ2 fuses intact? Is the 12VDC supply present at the injectors? What are the DC resistances of all six injectors? If one is below the 12Ω threshold it may be preventing any of them from operating (opening). With the injectors unplugged, is the ECM grounding the injectors correctly?

Thanks for the quick reply. Haven't got that far yet, but will. Just found two wires (purple and yellow) leading from what looks like the coil module forward and under the front of oil pan around to other side of engine. They were twisted together and missing the insulation. Wires had been mashed together because of a bad motor mount I think. Will repair them and see what happens then. While changing fuel filter, I turned switch on and the fuel sprayed out ever where, so I'
m pretty sure the pump is ok. Just replaced the fuel pressure regulator two months ago. Also thinking about replacing the cps if fixing these wires don't help. Will get back to you with results, and thanks again for the help.

I assume, this is a 3.1 "Multiport" engine? The difference between a multiport and a sequential engine is a cam sensor....multiports don't have one....so when they fire injectors, they fire them in groups of three(1-3-5, 2-4-6), instead of individually.....if one injector in that group of three is shorted, it draws too much current and the injector driver in the ECM that drives the injectors will shut down and not fire them......I think this is what Blue Bowtie is alluding to.....

If you have spark, this means the crank sensor is ok.....so get a can of carb cleaner, open the throttle body, and spray some carb cleaner into the upper plenum.....wait a few seconds, close the throttle plate....have someone attempt to start the vehicle.....spray carb cleaner at the closed throttle plate.....if car starts and runs as long as you spray, then he injectors are not firing if fuel pressure is ok.....

Many times, I have seen mice build little nests under the upper plenum and they like to eat injector harnesses.....if multiport, measuring resistance at the bulk connector, the resistance should be 4 ohms(three 12 ohm injectors in parallel)......

Thanks Tech II, it's multiport, but I did change the crank sensor today. Nothing helped although it did back fire once when I first tried to start it. Then just spun over. Got to work tomorrow so may not get back to it for a few days as it will be dark when I get home, and were expecting some winter mix. Sprayed some starting fluid in it with no results also. Was by myself, so I held throttle open and sprayed. All wires and plugs are new as is fuel filter. Guess its time to remove intake and try to check those injectors out. So if I get a lower reading than 12, one or more of those three injectors are bad? Will read up some more in the Haynes manual about testing so maybe I can get a better understanding of how to do this. Tried to pull any codes by jumping terminal's A&B, but no codes came up. Just flashed 12 over and over and fan would come on. Wish it was OBDII. Thanks again guy's

Looking at this diagram, you can check the resistance without removing the plenum....you disconnect the injector harness, and attach your ohm meter to the half going under the plenum.....

Let's start with the 2-4-6 injectors.......with the meter on a low ohm scale, attach one lead to the pink/blk connector in the harness and the other lead to the lt blue wire connector in the harness.......since all injectors should be about 12 ohms, 3 in parallel would read 12/3 or 4 ohms.....if one was open, it would measure 6 ohms.....if two were open, it would measure 12 ohms .....if all were open, it would measure infinite......if one injector is shorted, it will read zero......

now attach the leads to pink-blk and lt green, and as before, you should be getting 4 ohms.....some diagrams show a separate pink-blk for each trio of injectors, some only show one....

http://i.fixya.net/uploads/images/dttech_127.gif

Thanks again Tech II, This is great to learn. was dreading tearing it apart just to test. Wont mind so much is test calls for it though. This info isn't in the Haynes manual, and I really appreciate you're guidance here. The weather is messy now, but I'll get on it as soon as I can. Will update as soon as I can. Thanks again!

Back again, I couldn't really tell what was what at the harness as their were two light blue wires and two green wires there. Took plenum off and found two injectors on cylinders one and five were pink and blue while cylinder three was green and yellow. Same thing on front side with #two and four being green and yellow, and #six was pink and blue. :banghead:Probed each injector and got 2.1ohms on each. When trying to probe the harness end, it would just flash numbers all over the place.

OK, here is another schematic:

http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0900c152/80/06/80/c4/large/0900c152800680c4.gif

the key is the light green and light blue control circuits......

What is confusing about those injectors is they are not really in the place that they actually look....if you look at the lower intake you will see a casting number(from 1-6) that the injector hole actually feeds(kind of crosses over to the opposite side)....so look at the "runners" in the lower intake going to the injector holes, and you will see the casting number of the cylinder it actually feeds...the even numbered injectors will have the light blue control wire, and the odd numbered will have the light green.....power feeds in this harness are pink for 1-3-5, and yellow(in your case) for 2-4-6......

However, the ohms reading, directly from each injector should be 12 ohms.....an ohm reading from yellow to light blue, should be 4 ohms(with injectors connected, but main harness disconnected.....4 ohms from pink to light green.....

Well it's jumped timing. Swapped out the ecm with no luck. Didn't have a compression gauge, but pulled front valve cover to watch for movement of valve train. There wasn't any when cranked. Pulled all rocker arms on front bank and didn't find any bent push rods. Back bank will be a bugger to get to. Don't guess I could leave that side alone and hope for best could I? Also, will need to brush up on valve adjustment now. Thanks for all your help. Should have checked this out first.

IF there is no valve motion on ANY of the valve on the left (front) bank of cylinders with the engine cranking, the chain may have failed, cam snapped, or some other mechanical failure of the valve train has occurred. It's most common for the cam to snap at the rear cylinders in this engine, leaving the front cylinders' valve train operating, but anything can happen.

As for the valve train, there will be no adjustment. Rocker pivot pedestal bolts are torqued to a value, leaving the lifters to adjust lash hydraulically. These pedestal bolts are also known to pull out of the heads, stripping the aluminum along the way. Repair of this requires installation of a thread insert, so be careful about disassembly and the torque value upon assembly.

http://www.wwdsltd.com/files/191V6RockerPulled.jpg

It may be possible to remove the accessories, water pump, balancer, timing cover, and timing set with the engine in place given the extra space provided in the Lumina body, but it can still be tight.

PROCEDURE
Remove the air cleaner assembly. Disconnect the negative battery cable. Drain the cooling system into a suitable container. Remove the serpentine belt and the belt tensioner. Remove the alternator-to-bracket bolts and remove the alternator, with the wires attached, then support it out of the way. Unfasten the power steering pump-to-bracket bolts and support it out of the way. Do not disconnect the pressure hoses. Raise and safely support the vehicle. Remove the right side inner fender splash shield. Remove the flywheel dust cover. Using a suitable crankshaft pulley puller tool, remove the crankshaft damper. Label and disconnect the starter wires, then remove the starter. Drain the engine oil into a suitable container, then remove the oil pan. Remove the lower front cover bolts. Carefully lower the vehicle. Disconnect the radiator hose from the water pump. Detach the heater coolant hose from the cooling system filler pipe. Remove the bypass and overflow hoses. Remove the water pump pulley. Disconnect the canister purge hose. Remove the spark plug wire shield from the water pump. Unfasten the upper front cover-to-engine bolts, then remove the front cover. Remove and discard the gasket. Clean front cover mounting surfaces.

Given all that, you may want to be certain the timing chain is the prime suspect before digging in.

Thanks for your reply. That rocker arm isn't like mine. Mine aren't pedestal type. Just plain rocker arms with a half round insert and nut holding them tight. Got it tore down to where I need a puller to get harmonic balancer off. Then I can remove the timing cover. I assume this is an earlier model. Haynes didn't mention Bringing #1 piston to TDC on compression stroke, but does say on later models to set #1 on TDC (on compression stroke I assume).Does this mean that if mines the older model, I need not worry about getting #1 to TDC? Just make sure both crank shaft and camshaft marks are at 12 o'clock? Page 2D-10 in manual under removal.. Also on same page on removing the timing cover, seems like a lot stuff to remove unless I've missed something. Thanks again.

If you have the early 2.8/3.1 heads they will have the straight valves and older style (hemispherical ball) rockers as you describe. That rocker assembly is from a slightly newer ('96-ish) 3.1, and I thought that came into effect in 1990/91 - Evidently I was mistaken.

You will need to get #1 to TDC to align the timing chain sprocket marks, and it may be easier to do that now unless you have a crank snout socket or other means to turn the crank with the balancer off.

Wow, no valve movement on 2-4-6 push rods?

If a camshaft, there is no room for replacement......would seriously consider looking for another motor...

Hadn't considered the cam braking. With timing chain off, would I be able to turn cam, or even pull it in and out some? Guess not with the lifters still in the engine. But if chain is broke or gears striped, replacing that part would let me then roll engine over and tell if valves are again working. If something catches while turning it over I'll know something's broke in there. As far as getting #1 to top dead center, I'm having a time trying to find compression stroke as the rocker arms are off on front side of engine and air escapes there as engine is hand turned. Cant reach deep enough into #1 hole to plug it with finger and feel for compression. Mark on damper is lined up with mark on timing chain cover. Is it important that I find compression stroke as the ECM will do the timing? Really appreciate all your guidance guys.

If chain broke, gear stripped, or cam snapped, hard to believe that there wouldn't be a bent valve, push rod, etc.

I got the timing chain cover off and found chain broke and part of the damper metal crushed between cam sprocket teeth and chain before it broke. no plastic was left from the damper. Guess it went into the oil pan to get sucked into oil pump. Noted end play of cam was about 1/4" in and out. Rotating cam sprocket by hand all lifters moved up and down. As far as bent push rods go, I did find the short rod for #5 cylinder slightly bowed and also noticed there was fuel in all ports in heads except for #5. I'm talking plenty! Has #5 got a stuck open exhaust valve that allowed fuel to exit while all other cylinders held fuel? Do you think this is normal or does it indicate problems with #5? Wondered if maybe that valve was open when chain broke, but looks like more than one valve would be somewhat open. Guessing now. Don't want to throw much more money at this if you guys say its a lost cause. Any advise is appreciated.

The fuel likely pooled in the intake ports from the injectors firing as you attempted to start the engine. #5 may have a leaking or bent valve, allowing the fuel to pass the valve and not pool in the intake port.

If the camshaft can be turned and the valves operate, the engine MAY run with a new timing chain. However, the bent push rod on #5 could be an indication of the piston slamming the valve. That would explain why #5 intake port has no fuel pooled in the intake port, and may also indicate other damage.

One thing to remember is that the oil pump pickup includes a screen, so larger chunks will not likely get pulled into the pump. The missing plastic from the tensioner slider may not be as great a problem as you might presume, especially if draining the oil can clean out the larger bits.

Also, if the #5 push rod was only slightly warped, the valve does not stick in its guide (no bent stems), the valves in #5 move as far as the other cylinders (no bent faces), and you can use a leakage tester and air supply to create pressure in #5 without excessive leakage into the crankcase or out a manifold, the valves and piston may be intact. If there is leakage into the manifolds, that would indicate a valve sealing problem. If there is leakage into the crankcase, that could indicate a holed piston. If the engine passes all these tests, a timing chain and tensioner, new push rods, fluids and gaskets may solve the issue.

Unfortunately, there is an equal chance that piston/valve damage occurred. You'll have to perform the evaluation, and act accordingly. If the car is worth the effort and expense, it may be worthwhile to tear into it further. If a lower mileage used engine is available, that may be another option. You'll need to consider whether the car is worth the expense and effort.

Advice needed one more time. Timing chain was broken. Had eaten the dampener up really bad. Most of it is likely in oil pan. Valve on #5 cylinder(one with short push rod also bowed)is stuck open. All other push rods looked good, and fuel had filled up the valve ports from cranking on it so much. Only #5 was empty because of bent valve. Do you think piston was damaged also? Had to work, and wont get head off until Friday. Looking for a good used head and want to know if both heads are the same, or does replacement head have to come from same side of engine as mine. E-bay mentions naturally aspirated only. That wont work for me will it as mines fuel injected? Learning as I go here. My tool box is looking like it needs an addition added on to hold all the new tools I've had to buy. This is a charity case job for a disabled single mom on fixed income, and I cant buy her a car. So I'm just trying to patch it up as best I can. I work for free and usually buy all the parts, but she caught me at a bad time this time. Ireally appreciate all the good advice you folks have given me . This is the best site to get help. I'll start a new thread for future problems. Thank you all.

I'm sorry, Didn't see your post until I posted .You answered all my questions. Finding another engine may be my best bet. Will get that head off Friday as I'm off. Really hoping the piston looks ok. Could actually see fuel pooled on piston top below valve with flashlight while rocking car some. Valve was stuck open just enough to see reflection of slushing fuel in cylinder. You and Tech ll have really been of great help for me and I'm really grateful .You guys are what make this site so great.

If the valve in #5 is bent, you MAY be able to extract it and replace with another valve, but there may also be guide damage. Pulling the head is safest to inspect the piston top. If it is only marked and not cracked or holed, it may be serviceable - Photos would help.

Once the head is off you might take a shot at the valve. If you're lucky the guide is not beyond use with a new valve,stem seal, and of course a push rod - About $10 for a valve, $2 for a guide sleeve, $2 for a seal, and $3 for a pushrod.. A used head is also a possibility, but only if the piston is intact. For a $50 timing set w/damper and valve parts, and another $100 in gaskets, it may be cheaper than a replacement engine, or maybe not. Then again, swapping out the engine is quite a bit more work.

Good for you to be helping someone in need - I appreciate that. I'll be checking in to help if I can, and it appears others are on the case as well.