Bad Miss followed by Loud clunk when restarting

[goody90q45]

Driving to work this morning and after a WOT to about 80 mph on the freeway onramp to the next offramp 1/8 mile away the engine developed a bad miss. I limped the next 1/2 mile to work with the miss and the engine barely able to stay running, pulled into a parking spot and the engine died.

Tried to restart and it cranks for 1/2 second and then a loud clunk. Turned the key on twice more and got only clicks but on the third try the engine turned over again followed by another loud clunk. Prior to this morning the engine had been running flawlessly.

I'm having it towed home this afternoon but don't have a clue what could have caused the miss and clunking. Sounds suspiciously like a timing chain problem but this is a '94. BTW- I'd been hearing an intermittent rattle on startup the last 3 days that sounded just like a loose heat shield but it went away after warm up. Didn't get a chance to look into it this weekend but could it be related to my current problem?

Any help would be appreciated.
Modified by goody94q45 at 4:56 AM 4/18/2006

[maxnix]

Damn, hope you didn't spin a bearing.

Doesn't seem like a failed injector could cause that unless it caused a hydraulic lock and then bent a rod.

Compression test next?

Keep us posted.

[PopPop]

May have jumped time! Like Brian said clunking noise usually is made by a spun Rod Bearing if it's an actual clunking sound.

[goody90q45]

Did a quick look today after getting it towed home and the connector to one of the Valve Timing Control (VTC) Solenoids had come loose. This is the unit on the end of the head above the crank angle sensor. There is a matching VTC on the other head.

I plugged it back in and she still wouldn't turn over. What would losing one of the two VTC's while driving do to an engine? A spun rod bearing sounds terminal?

[Q45tech]

Losing VVT control will only show above 4600 rpm as a bit of roughness.

How many miles on engine? Oil type and frequency since brand new?

[goody90q45]

Thanks for the response. Engine has 134000 miles. Regular service by dealership for the first 4 years then spotty after that. I have owned her since May 05 and changed oil regularly as well as all other fluids.

When the engine started missing on the offramp it was at all rpms and there were no strange noises. The clunk occurred after it stalled when I tried to restart the engine.

Brian- The engine is not turning over at all now (it's not the battery) so I really can't measure compression. BTW- What is the proper way to manually rotate the crankshaft.

[elwesso]

I think its a 30mm socket that you can use to turn it with a 1/2in drive socket.....

I cant remember exactly ubt its in the timing guide writeup.

[Q45tech]

Is your regular oil change every 90 days per FSM.....what was worse case oil pressure hot when you acquired the car in May 05?

Unusal for even sludge buckets to fail before showing an oil light [it does work on key turn correct?]

[maxnix]

This is not sounding good at all! If the battery can't crank it, a rachet with a handle ten feet long won't either.

Might check the articles on shopping for and rehabilitating a JDM take out. Just in case.
Modified by maxnix at 6:09 AM 4/13/2006

[goody90q45]

It quit raining long enough today to allow me to go check ECU codes (Ya, I know I'm spoiled with our CA weather since a lot of you guys work in blizzards).

The only code I got was 11- Camshaft position sensor (CPS) circuit. I searched NICO with no luck and now I am perusing the FSM for the steps to troubleshoot the circuit.

Could this malfunction cause the miss while driving and the clunk I hear when trying to start the engine? Is the ECU locking out the starter until the CPS circuit is repaired? Thanks in advance for your responses.

BTW- The oil light is working on key turn to on.

[Q45tech]

The starter IS NOT LOCKED OUT BY ECU.

The CAS failure will stop the plugs from firing..........something to think about is the injectors may have filled a cylinder with fuel as the CAS died and the engine shut down and was recranked.

Pull all spark plugs out and check before trying to recrank.

Check electrical connections on CAS............total failure is rare as there is a backup circuit in CAS module [limp mode rpm limit]

[goody90q45]

[QUOTE=Q45tech]The starter IS NOT LOCKED OUT BY ECU. The CAS failure will stop the plugs from firing..........something to think about is the injectors may have filled a cylinder with fuel as the CAS died and the engine shut down and was recranked.QUOTE]

Thanks Dennis. I tried to repost last night but my connection was down. I started to troubleshoot the CAS but it got dark. I think you are honing in on the problem though as when I disconnected the airbox there was raw fuel dripping out of the throttle body.

I did manage to get it to turn over last night before it clunked again. I've got everthing opened up and airing out now and will finish the CAS troubleshooting tonite to rule it out and then remove the plugs (and fuel pump fuse). Hopefully once I get the plugs out it will turn over and get rid of the excess fuel.

I really appreciate your help. I will repost again tonite and report my progress. Please check in in the morning. Thanks.

[elwesso]

Mike....

Take Tech's advice. If you have raw fuel coming out of the air intake you surely have hydrolocked things... DO NOT CRANK IT AGAIN WITHOUT TAKING THE PLUGS. You will want to put some oil down each of the plug holes because you likely washed the rings......

The CAS should go into failsafe if you unplug and at least allow it to fire but it looks like you've flooded it.....

[goody90q45]

Thanks Wes. How much oil should I put in each cylinder? It's all starting to make sense now and I am very relieved that I probably did not sieze my engine. I will finish troubleshooting the CAS tonight and then take out the plugs and continue from there.

[elwesso]

You're not home free yet.. You could have possibly hydrolocked it and it could be bad, but maybe not... HOPEFULLY not.....

what I would do is put about an ounce of oil or so in...Not a lot just a little...You will obviosuly have to change the oil as its probably filled with gas... Check the oil asap and let us know ifits way up and looks really thin... in fact, i would change the oil very soon after marking sure thats what the problem is.. basically i want you to crank it and make sure that the engine runs, and then shut it down immediately and drain the oil...

[DominickJ30]

You dont have to put any oil into the cyliders.

Simply find the root of the CAS problem, take out the plugs, clear the flooding condish and see if you get spark after that.

Then check your oil and, you will probably have to change it.

[96Qowner]

Just a clarification ... he said he got a code for the Cam Position Sensor.

The only code I got was 11- Camshaft position sensor (CPS) circuit.

Could this malfunction cause the miss while driving and the clunk I hear when trying to start the engine? Is the ECU locking out the starter until the CPS circuit is repaired? Thanks in advance for your responses.

I had a code for the CPS when I first got my car, and it ran fine - no clunking.

[maxnix]

Just a clarification ... he said he got a code for the Cam Position Sensor.

I had a code for the CPS when I first got my car, and it ran fine - no clunking.

NA as you have OBD II.

[daegrigg]

I hate to even suggest this but this has some of the symptoms of valve/piston interference.

If the valve timing has slipped enough you will get piston to valve clunk (and probably bent valves). If the VH4.5 is an interference engine (someone please verify), I would verify that the cams are timed correctly before trying to fire up the engine.

Good luck.

[goody90q45]

Let me start by saying I really appreciate all the help and advice I've gotten from all the responders. I'm working through this step-by-step and I could not do it without your input. Thank you all.

Today- I took out the spark plugs (much easier the second time) and got almost all the way through the diagnosis of the camshaft position sensor circuit (ECU code 11) per the FSM.

The plugs on the drivers side (1-3-5-7) all look normal. They've only been in for less than 5000 miles. Plugs on the passengers side (2-4-6-8) all had a light oil coating and were dripping raw fuel.

Camshaft position sensor (CAS?) circuit- I did the continuity checks and all is OK. The final step is to remove the CAS and do a easy check using a VOM.

Questions for today-

I see a scribe mark on the CAS and it looks like it has to be aligned the same as it came out when reinstalling. I'm pretty sure I've read about this in a recent post and I'll be reading the FSM and some posts tonite. Any tips on removal/installation would be helpful.

VVT- I know Dennis said that the VVT plug that came disconnected would not have caused any problem below 4600 rpm but it seems like the disconnected VVT plug, which was on the passengers side, and the gas soaked spark plugs, also on the passengers side might be related. I was at about 5000+ rpm when the problem started.

I didn't try and turn the engine over today. I'm going to light a few candles in church tonite while the cylinders air out and then try it in the morning. I assume I should crank it over (if it cranks) for a bit before reinstalling the plugs.

Final question- Where do I go from here, and am I on the right path? Thanks again to everyone for your input.

[elwesso]

Mikey your on the right track...

OBviously only one bank is affected... Certainly does seem coincidental that it would start flooding one side...

At this point it doesnt seem to me like yor dealing with a valve-piston pattycake situation (VH45 is an interference engine), but more likely a flood situation... The question remains is WHY so much fuel is being dumped in there....

Upon trying to start it, i would leave everything easy to remove.. dont necessarly screw down the coils and stuff, just plug it all in to make sure it works... Just a time saver if you have to rip it all apart again...

Theres only one way you can put the CAS in, it wont seat all the way if its not in correctly....

I would definitely crank it over a few times.. With the plugs out or at least half of them it should be nice and snappy...

[96Qowner]

Arg, sorry to break in again, but I'm seeing Crank Angle Sensor (CAS) and Cam Position Sensor (CPS) being used as if they were the same thing. Does a code for the CPS imply that the there's something wrong with the CAS? Or are they the same thing.

Just for future readers of the thread and for myself, whose mind just can't DEAL with non-linear logic, heheh.

[goody90q45]

Good News. Followed your advice, and after airing everything out overnight, put it all back together and she fired right up. Drove it around the block, spewing some black smoke and missing real bad and can't go much more than 30mph. Engine sounds fine with no strange noises. Looks like hydrolock was my problem. I'm really relieved that the problem was not a siezed engine.

Bad news. Still have the same symptoms but now with raw gas dripping off the exhaust manifold below the car at the PS cat. I probably had the same thing at work when she originally died but didn't notice it. Based on what I saw when I removed the plugs it looks like the passenger side is not firing and raw gas is pouring through the cylinders into the manifold (?). This time though I pulled the fuel pump fuse and ran the engine till it died to avoid another hydrolock incident.

I know I've got a lot of troubleshoooting ahead but this is all new to me. I've been reading a lot of posts and it looks like I should start by checking spark, or at least voltage out of the coilpacks since I would prefer not to run the engine. About the only thing I've done so far is check the ECU codes, got code 34 (knock sensor).

I'm can't find the troubleshoot for the power transistor unit in the FSM or on NICO. This is one thing all 4 cylinders have in common. Any advice would be appreciated.

[elwesso]

Its very possible IMO that you are getting spark but the injectors are somehow staying open much longer than they should (or possibly never even closing)... EVEN if you arent firing it shouldnt dump that much gas through....

Im kinda leaning toward an injector harness related issue... Im not sure how they woudl get stuck on, especially just one side...

Its hard to say, im just not really sure at this point...

I think the frist thing id probably do is check to make sure you do get spark.. Remember you have to ground theplug on the plenum. You cant get a good ground on the VC...

I think youll likely find that you have adequate spark.. the Q ignition system doestn tend to fail, while the fuel system kinda does...

[Q45tech]

Try a spare ecu have seen a failure such as you describe.

Remember each injector receives +12V via a common fuse [behind battery] and each injector ground terminal goes to a separte switching transistor in ecu.............each bank of transistors is driven by a separate IC in ecu.

Read the wires [socket going to ecu] are all [2,4,6,8] at ground with ecu turned on?

[maxnix]

Do you have a modified ECU?

Check the board for solder bleeds and the like if you do.

[3Q Jay]

Mike- i just found this thread. i have a spare 94 ECU (tcs model) that you may borrow for troubleshooting--just pay 2 way shipping. let me know

my first thought on the rt bank vs. left bank was ecu--but just a guess.

don't keep running it with all that fuel messin round. bad things lurking nearby (fire, permanent compression loss, bent rod....)

[goody90q45]

[QUOTE=GQ Jay]Mike- i just found this thread. i have a spare 94 ECU (tcs model) that you may borrow for troubleshooting--just pay 2 way shipping. let me knowQUOTE]

Brian / Jay / Tech / Wes- I've got the standard ECU and have not done the upgrade. I am definately not driving until I get the problem fixed. In fact, I'm running her dry every time I test the engine by pulling the fuel pump fuse.

Jay- I hadn't thought about the ECU being the problem and I really don't have anyone local that could loan me one. If your TCS model will work for a short swap out in a base model Q I'll take you up on your offer. I'll email you now. Thanks

[elwesso]

Mike for your purposes it will be fine. may throw a TCS code or something but the car will operate as it should.

[3Q Jay]

Mike- spare ECU comin at you. While you're waiting, how's the spark look?