Backfiring inside intake? No power, bogs down...out of timing?

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HawleyTronics

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My 2000 LS V8 has had some work done to it within the past couple of years. I have had it in the garage and paid $1,800 for them to screw me and only change the lower timing chains and tensioners, they never touched the upper ones. Last summer I ended up having the change the passenger-side upper tensioner and chain when the tensioner broke and the chain jumped a couple of teeth. All went well and it has been running great since.

Then last Friday I was on the highway and all of a sudden it started running like crap, no power, making all kinds of noise in the center of the engine and I managed to limp it home. When I start it up, it sounds like someone knocking on the inside of the intake, pretty much sounds like backfiring in the intake.

I pulled the left valve cover again and looked at the timing chains and tensioners as well as the cams and valve seats. Everything looks fine and clean. (This is the side I fixed over the summer)

Last night I started to pull the driver-side valve cover and gave up after a while when I got to 4 bolts that are a bitch to remove because of space-restriction. I will continue trying to remove that valve cover tonight.

I am assuming that maybe that upper chain has jumped a couple of teeth to throw the timing off? I think that since that is the last tensioner that has not been worked on yet that maybe it has failed and the chain may be loose?

There is NO sound coming from the valve covers, like it did before when the passenger-side upper timing chain was loose and was slapping the inside cover. The only noise is that banging/backfiring sound coming from just inside the intake in the center of the engine. I can tell it is not in the lower part in the engine, but sounds like it is right in the upper-most part of the intake.

Do my assumptions sounds correct in that I think it may be out of timing again?

Any other ideas?

I just want a little more information in case I get the driver-side valve cover off and everything looks fine there as well.

I have had issues with coils in the past and have replaced many of them (at least 5) and as badly as it is running right now, I don't think it is coil-related as it would seem that for it to be running this badly at least 4 of them would have to have failed.

Any ideas? Anyone else ever have this issue?

My friends all say "ditch the LS and get another car", but I love this hunk of mechanical failure, so I think it is worth dropping a couple more $100 bills into since the rest of the car is solid and clean.
 
Sounds like the driver side chain... get the vc off before you do anything else... most likely (from your description) that side chain has broke.... make sure you have a good set of swivels and extensions to remove it...
 
Yeah, I realized last night that I am going to need some swivels to get those 4 remaining bolts off. What a P.I.T.A.!

Looks like I may be ordering another upper chain and jaguar tensioner from that same dealer on eBay again. They were great! I lost one of the master links and they shipped me 3 more, and arrived 3 days later, for free. So if it comes down to it, I have no problem purchasing more parts from them! It was around $180 for the chain and tensioner.

Thanks for the input, I will post my findings for others' reference...if any.
 
HawleyTronics said:
Yeah, I realized last night that I am going to need some swivels to get those 4 remaining bolts off. What a P.I.T.A.!

Looks like I may be ordering another upper chain and jaguar tensioner from that same dealer on eBay again. They were great! I lost one of the master links and they shipped me 3 more, and arrived 3 days later, for free. So if it comes down to it, I have no problem purchasing more parts from them! It was around $180 for the chain and tensioner.

Thanks for the input, I will post my findings for others' reference...if any.
Click to expand...

If it broke, you probably have valve damage too.
 
On the 3 lower drivers side VC bolts, extensions with a U-Joint are best, along with a telescoping magnet to fit the socket on the bolt. For the rear bolt by the booster, the best way I found was to use the setup in the picture to get the right height, and reach behind the drivers side head. >>3/8" 10mm 6pt > 1/4" to 3/8" adapter > 1/4" ratchet.

For the bottom rear COP cover I just use a 6pt 7mm combination wrench, again from behind.

DSCN1102.jpg
 
Yeah, I was thinking that too, joegr. If the chain is broken, do I bother buying another chain and tensioner and hope for the best, or do I need to pull heads and get really dirty?

Or is it even worth it at that point?

I didn't get around to pulling the driver-side VC last night. I couldn't find the right tools to get those last 4 bolts off. I will need to get a swivel socket elbow I think before i attempt it again.
 
I have the EXACT same issue on my other LS, Opened up the VC on drivers side and the chain was just laying there. I'll be ordering a new chain and installing to see what happens.
 
The thing is, if that chain broke (even the secondary) wouldn't the car not run at all?

Mine still runs (was even able to get it home from about 5 miles away) but has no power and backfiring, obviously due to being out of timing.

I would think that if the chain is broken then that side of the engine would not be firing correctly and I think it would not run at all...
 
Im surprised he made it home (if this is the case)... i could get mine to run, but just barely.... (like it was only running off 4 cylinders :p)
 
That may be the case then, it was running very badly, but I was able to go at least about 40mph and up hills at times, so I have my fingers crossed that the pistons and valves didn't become too cozy from this happening and maybe the timing is just way out of whack...

The only thing to do is see if the chain broke and replace it if it did. Then see how it runs before going any deeper into the engine. The way I look at it, if the chain is damaged or broken, I will need to replace it anyway.

This is just so frustrating. I love this car, but I keep asking myself WHY I love it...LOL
 
I removed both valve covers and inspected the chains and tensioners as well as the cams and valve seats, and everything looks good and clean. Nothing is loose and nothing looks out of place or faulty. So I have no clue at this point what the hell it could be.

Mass Airflow Sensor?

Multiple Coils gone bad??

Bad Emissions Computer (brain)???

Broken Valve????
 
HawleyTronics said:
I removed both valve covers and inspected the chains and tensioners as well as the cams and valve seats, and everything looks good and clean. Nothing is loose and nothing looks out of place or faulty. So I have no clue at this point what the hell it could be.

Mass Airflow Sensor?

Multiple Coils gone bad??

Bad Emissions Computer (brain)???

Broken Valve????
Click to expand...

Bump the starter around until all the flats (at the front) of the cams line up. If one doesn't line up, then that one jumped time. Might as well be sure that there's no timing chain issue before moving on to other suspects.

Also, add to your list the crankshaft position sensor.
 
Already checked that. One of the first things I checked since I had replaced the passenger-side secondary chain and tensioner over the summer and that's how I timed it.

The timing chains are all nice and tight, the cams are fine and are lined up correctly, timing chain tensioners are all in-tact, valve seats are all fine, and everything looks nice and clean. So I have to do some more research...
 
I am going to put the valve covers back on tonight. I should be receiving this in the mail tomorrow: Amazon.com: BAFX Brand - ELM 327 Bluetooth OBD2 scan tool - For check engine light and other diagnostics - Android compatible: Car Electronics

It is an OBD2 Bluetooth interface that can be used with Android phones as well as PCs that have bluetooth. I have software on both my Android phone and my lappy, waiting for this little wonder. I am hoping it will shed more light on the problem and allow me to pinpoint the issue(s).

Android SW: Torque Pro
PC SW: ProScan and ScanXL Pro
 
Note that's a very basic interface device, so you'll be limited to what your chosen SW package supports. And the freebie/cheap SW packages don't do much. You'll get basic code reading (not extended/ABS/manufacturer-unique codes), some very laggy sensor reading, and the ability to clear any trouble codes.
 
Look up the specs on the software I specified and you'll see those are pretty robust programs that can not only give me basic codes but can also diagnose most codes, analyze 1/4 mile, 0-60, HP and torque ratings and much more. I can clear the CEL as well as load plugins for Ford vehicles to give me more detailed testing capabilities. The Android app can even track GPS coordinates while driving so you can see how your vehicle runs throughout your whole trip.
 
OK, I ran ScanXL Pro software and got the following codes:

P0156 - 02 Circuit (Bank 2 Sensor 2)
P0301 - Cylinder 1 Misfire
P0303 - Cylinder 3 Misfire
P0304 - Cylinder 4 Misfire
P1000 - OBD Systems Readiness test Not Complete
C1235 - Right Rear Wheel Speed Sensor Input Signal Missing
B1499 - Lamp Turn Signal Left Circuit Failure

The last 3 codes are not relevant for what I am diagnosing right now...I know the turn signal is loose and the speed sensor is probably disconnected when my girlfriend went over a series of bumps a couple of weeks ago.

I think it is strange that the P030x codes seem to signify that the misfires are on one side of the engine (Cylinders 1,3 and 4). And the 02 Circuit I am thinking maybe a bad 02 sensor, but would the O2 sensor cause my car to run like it is, with the backfiring in the intake and the misfire codes?? And those are the cylinders on the side of the engine that I repaired over the summer, with the new timing chain and tensioner, etc. And everything looks fine on both sides in regards to timing chains, etc.

Any ideas? Where should I start? LOL

I am also thinking I should clear all the codes, put everything back together and run the car and see what codes arrise from that. Maybe some of these are old stored codes even though the CEL wasn't lit all the time?
 
That's all really weird. I think I'd do a compression test, and check the fuel pressure.
 
I think what I'm going to do first is put everything back together and then clear the current codes. I will swap the coils from both sides of the engine and see if the problem follows the coils. I would assume that if the cylinders 1, 3 and 4 coils were bad (according to the current OBD codes), the cylinders on the driver side of the engine would now be throwing codes.

I am trying to eliminate the problems one-by-one without getting too financially involved if I don't have to.

That OBD2 Interface was well worth the $40 I spent on it since I can use that with any vehicle 1996 and newer. I just don't want to have to go out and spend another $50 on a compression tester unless I have eliminated other things first.
 
HawleyTronics said:
Look up the specs on the software I specified and you'll see those are pretty robust programs that can not only give me basic codes but can also diagnose most codes, analyze 1/4 mile, 0-60, HP and torque ratings and much more. I can clear the CEL as well as load plugins for Ford vehicles to give me more detailed testing capabilities. The Android app can even track GPS coordinates while driving so you can see how your vehicle runs throughout your whole trip.
Click to expand...

Sure, but it's $250 to get the SW package that will do vendor specific codes. That's a little better than their competitors (no hardware included, so it should be somewhat cheaper).
The problem with el-cheapo bluetooth interface chips is the transmit speed. You'll only get a few reads per second at best. Hardwired scanners can do tens to hundreds of reads per second.
Every software package advertises the stuff you have above. Doesn't mean it actually works well. The performance measures won't compare to a dedicated unit like a GTech.
Just for reference, I also have a bluetooth interface and use it regularly. I find it useful to have an accurate understanding of its capabilities, though.
 
I do have the Ford code extensions. That is how I was able to get the following codes as well:

C1235 - Right Rear Wheel Speed Sensor Input Signal Missing
B1499 - Lamp Turn Signal Left Circuit Failure

I know the Bluetooth may not be as fast as a more professional hard-wired unit, but I just need a reading of the codes and not necessarily a constant, to-the-millisecond, reading.

I pulled the plugs last night and the cylinder 3 and 4 plugs were black with carbon. So today I am buying a set of plugs and that Bank2/Sensor2 Oxygen sensor and taking it from there...

Any other suggestions?
 
HawleyTronics said:
...
Any other suggestions?
Click to expand...

Borrow a compression tester from an auto store? (Most will loan them out at no charge. You put down a deposit that is the value of the tool, but they refund it when you bring it back.)

I don't see the point of replacing the O2 sensor until figure out what is going on. Sensor2 has no bearing on the mixture control or running of the engine. It's just there to turn the light on if you have a bad cat.
 
Bought an O2 Sensor and 8 plugs but those made no difference. I fired her up and still runs the same. Borrowing a compression tester from Autozone tomorrow. I will either confirm or eliminate the valves tomorrow...
 
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