Rougher idling after timing belt change (2 Viewers)

[lxj1]

2002 LX 146k miles. I (not a mechanic) changed the timing belt, water pump, fan bracket, serpentine belt, and pulleys.

When I’m idling at the stop light, it’s a little rougher than before. Not like it’s misfiring or anything, just vibrating a little more, enough that you’d see ripples holding a glass of water.

When I put in neutral the vibration goes away. It was not like this before the timing belt change.

What could this be? How might I troubleshoot?

 

[xplore]

If the only thing that was touched was the timing belt components, then I would suspect that one or both of the heads is slightly out of time. Are you positive that all of the timing marks were dead on for the crank shaft and both heads after you installed the belt?

 

[lxj1]

Are you positive that all of the timing marks were dead on for the crank shaft and both heads after you installed the belt?

I don’t have a good picture of the left cam but I’m positive it was all lined up. Btw I did also change the radiator and all coolant hoses too but didn’t think that would be relevant.

What does it mean when the vibration stops when putting in neutral? I have noticed that tendency in other cars too.

 

[xplore]

I don’t have a good picture of the left cam but I’m positive it was all lined up. Btw I did also change the radiator and all coolant hoses too but didn’t think that would be relevant.

What does it mean when the vibration stops when putting in neutral? I have noticed that tendency in other cars too.

The tendency to stop vibrating when in N probably has more to do with the RPM. I'd bet that if you had it parked at a stop light when its vibrating that it would stop if you applied a little bit of gas.

If the timing is indeed dead on, I would look at the crank and cam position sensors. I believe one of them is accessible on the front side of the engine when doing the timing change. That could be something to look into. It might be something as simple as a bad connection.

 

[Patassa]

Sometimes we have something akin to a redneck cousin of placebo affect, where we make a change and become hypersenstive to things that were always there.

 

[lxj1]

The tendency to stop vibrating when in N probably has more to do with the RPM.

Right. When I’m at a stop light in drive, tach shows 600 which sounds low. When I put in neutral or park it’s closer to 800. I guess the question is why my RPM is low and what I can do about that?

Sometimes we have something akin to a redneck cousin of placebo affect, where we make a change and become hypersenstive to things that were always there.

This could also be true but I’m pretty sure it’s not in my imagination!

 

[abuck99]

RPM spec is illustrated in the FSM; but IIRC with A/C on RPM spec is in mid 600's, and A/C off Mid 700's.

Looks like you got the belt on the right marks but was the crank (at "0" ) & cams in the right position when you installed the belt?

More info here: Timing belt alignment.... - https://forum.ih8mud.com/threads/timing-belt-alignment.1157484/post-12566321

 

[2001LC]

It is important to spin the crank 720 degrees, and check hard timing marks (belt will not line back up), as FSM recommends. But I doubt your out of time. As I would "think" (don't know), it would run much worse than a "D" vibration. But I don't know that, as I've never been off timing hard marks. Well except one case I took on, someone else botched the job. Which I was told: At first just ran rough: Timing belt job just done. Blown engine or savable? This is interesting guys! - https://forum.ih8mud.com/threads/timing-belt-job-just-done-blown-engine-or-savable-this-is-interesting-guys.1182445/

The step just before checking hard timing marks. Is pulling the tensioner pin. You did torque in the tensioner and pull the pin right! I see in crank/belt picture, belt is slack. Which indicates tension, not yet applied to belt.

It is more likely you've a vacuum leak and/or in need of a good tune. I dealt with the infamous "D" vibration, years ago. Before I found the "key" while doing a tune, to eliminating. Which was: disconnect battery (negative post) at being of tune (clean MAF, T-body, fix vacuum leaks, spark plugs, coils, etc..). Reconnect battery last. This reset computer, which it learns the tuned engine, rather than impose its old settings.

Few common vacuum leaks:
PCV hoses and grommet (98-02), oil cap rubber seal.
Vane pump idle up control duel vacuum lines.
EVAP vacuum lines at manifold/T-body
Air pipe, it's vacuum lines. Filter clean and it's seal seated properly. I fine 50% of air filter seals curled up, form not properly seating lid. Air pipe to throttle body not fitted properly. About 20% of the time, someone curls/folds lower (can't see portion) of plastic pipe to throttle body, which allow unfiltered air in, and is major vacuum leak.

If all else in-line (properly attached and tuned). Recheck hard timing. We can talk later on how!

 

[neoworm]

1st timing belt job?

You're probably being paranoid. lol

 

[J1000]

Did you disconnect the battery? It will be rough until it re-learns the idle. Also since changing the fan bracket (fan clutch assembly?) if you did not disconnect the battery then it might be rough because it is not re-learning the idle but parts have been changed.

 

[lxj1]

RPM spec is illustrated in the FSM; but IIRC with A/C on RPM spec is in mid 600's, and A/C off Mid 700's.

This makes sense. My RPM at 600 with AC off is low and that’s the vibration I’m feeling. Car is smooth as butter once I accelerate. My understanding is that a car out of time is very obvious.

It is more likely you've a vacuum leak and/or in need of a good tune. I dealt with the infamous "D" vibration, years ago. Before I found the "key" while doing a tune, to eliminating. Which was: disconnect battery (negative post) at being of tune (clean MAF, T-body, fix vacuum leaks, spark plugs, coils, etc..). Reconnect battery last. This reset computer, which it learns the tuned engine, rather than impose its old settings.

Few common vacuum leaks:
PCV hoses and grommet (98-02), oil cap rubber seal.
Vane pump idle up control duel vacuum lines.
EVAP vacuum lines at manifold/T-body
Air pipe, it's vacuum lines. Filter clean and it's seal seated properly. I fine 50% of air filter seals curled up, form not properly seating lid. Air pipe to throttle body not fitted properly. About 20% of the time, someone curls/folds lower (can't see portion) of plastic pipe to throttle body, which allow unfiltered air in, and is major vacuum leak.

I will look into these. Makes total sense. I was actually planning on replacing the PCV, grommet, and valve cover gaskets while doing the timing belt but the timing belt brought me to my knees and I decided to tackle other stuff later.

But I hate vacuum leaks after chasing one down on another car. I guess I will have to pull out my makeshift smoker again - Swisher Sweets cigars and a hand pump!

 

[gatormark91]

I'd forget about the timing belt, I bet a dollar that it is just a coil going bad. Coincidence. Same thing happened to me.

 

[lxj1]

I'd forget about the timing belt, I bet a dollar that it is just a coil going bad. Coincidence. Same thing happened to me.

No misfire or trouble code though, which is what I’d expect with a bad coil. It’s on my radar but gonna look for a vacuum leak first.

 

[2001LC]

This makes sense. My RPM at 600 with AC off is low and that’s the vibration I’m feeling. Car is smooth as butter once I accelerate. My understanding is that a car out of time is very obvious.



I will look into these. Makes total sense. I was actually planning on replacing the PCV, grommet, and valve cover gaskets while doing the timing belt but the timing belt brought me to my knees and I decided to tackle other stuff later.

But I hate vacuum leaks after chasing one down on another car. I guess I will have to pull out my makeshift smoker again - Swisher Sweets cigars and a hand pump!

Believe it or not. I've never replaced the head cover gaskets or tube seal. I've been 100% successful at just re-torquing head cover bolts to spec of 53IN-lbf. I've done about, 90 4.7L this way, none are leaking now. I use a digital torque wrench these days, or my HF 1/4". I always find them 1/4 to full turn loose. In one's, that someone replaced, I find bolt falling out most times.

I will be replacing one that has a tube seal leak. But we must because a "well know in mud" CA shop, Mess up. They replaced gaskets & seals and #1 tube seal is hanging halfway out in tube. Tube is filling with oil. Darn if one head did blow a spark plug out, within 200 miles of their service job. Client took to them as new purchase, asked them to get whatever needs done. he did his homework as to which shop best and drove 4 hours to them. Think they would have R&R spark plugs at 130K miles, while in there. As we all know, sparks are walking out of the 4.7L. Now it has a time-cert, low compression and dropping in that cylinder.

I'd forget about the timing belt, I bet a dollar that it is just a coil going bad. Coincidence. Same thing happened to me.

No misfire or trouble code though, which is what I’d expect with a bad coil. It’s on my radar but gonna look for a vacuum leak first.

Coil (COP) get a DTC (CEL) if trashed.

But weak old OEM or Chinese junk, don't aways.

Most time we can find by watching for misfire after warm and put under load. But just had one only misfires cold. Misfire was so minor, it would show may be 2 counts. The suddenly clear count back to zero. Had to really watch close. First time I thought was a glitch in teck stream. Near impossible to catch.

Client was a woman. She been driving her 98 since new, which now has ~370K miles. Turns out husband replace one coil few years ago w/parts store no name. He was sure it was #2 (BK2 ist plug in front). But #2 was Toyota Denso old stock OEM or looked so to me. #1 was a no name and a lighter color than Denso black.

What made even harder to find was she described as a sputter when cold. When first brought to me. I found it to be a very high mileage under maintained. I found many hoses and grommet vacuum leaks, 2 clamp on air box busted, T-body gunky, coolant low, serp belt and pulley bearings bad, fan clutch bad, transmission slipping and level wrong, etc. etc. Inspecting transmission I saw oil remnants on it's pan, but no leaks and localize oil. As if drained and not wipe off well. They said they had engine oil & filter done at lube shop. But never has transmision been touch or and ATF added. Yet they tow 5K lb horse trailer into mountains many times a yr. Transmission fluid level was off and color way to good, for use and miles. I tuned engine, coolant service and did full 12 qt flushed with M1 MV syn ATF. Running good and no more slippage, afterwards. Not perfect running as fuel trims a bit high, but acceptable at 4 to 7%. I poured in 2 cans of 44K, and said call if any issue. But I was very concerned with transmission heath. Not only should they have been flushing it every 60K miles. But I suspected lube shop pulled wrong plug and drain (3 or 4 qts) off transmission, then fill with who knows what cheap ATF. Then She used to tow again! OUCH!

First report sputter gone. Month later back. Dang could be transmision, I'm thinking!

Had her stop back by as she felt sputter. As she sat in driver seat idling while we talked. She said "there it is just now" "hear it, "I can feel it". I notice AC kicking on and off. That is what she felt. But I did get that misfire glitch before. So I said leave it with me tonight. I start cold in morning, hooked up to tech stream w/AC off. Sure enough next morning at OAT 38F engine cold start, a very minor sputter while I hooked to tech stream. 2 counts #1 misfire, then zero misfire count a split second later. After warm up no misfire at all underload or idling. Replace the #1 coil with a Denso, from know Denso supplier. Sputter gone no misfire cold or hot.

Been a few weeks now a client sent me a $50 tip and thank me for hanging in and digging in. Said they had taken too 3 shops over last 2 years (2 of which dealerships) with sputter issue, without results. Said it not run this well in 10 or 15 years.

Talk about knowing the feeling of your rig. She really did.

Well dang. Getting late, I better get out to shop.

I've another tough one in shop have to correct. 3 shops have tried a fail on. AHC OFF and bouchy. I've been digging in. I think I found what causes of which seems has now cascade further through the system. Issue went on to long. Now I need to fix cause, to see if I can find the damage caused by it. Spend 5 hours on it so far.

Been getting some difficult cases lately. One's I can't spot in field inspection.
One a squeek. Likely ball joint, but they all field test okay even spec with knuckle off.
One rotational thud. We strong evidence downstream of transmission and not likely transfer case or tires.
One ABS VSC setting off once in awhile. All usual suspects check okay.

 

[peacesells63]

Did you disconnect the battery? It will be rough until it re-learns the idle. Also since changing the fan bracket (fan clutch assembly?) if you did not disconnect the battery then it might be rough because it is not re-learning the idle but parts have been changed.

This.

Disconnect your battery for 1 minute then reconnect. Turn the key to the on position but do not start. Turn all accessories off (ac, fans, lights, stereo, etc). Don't touch the steering wheel, start the truck and let it idle until it is at full operating temp. Shut the truck off then re-start it and see if it is good. make sure you battery is good and fully charged before doing this.

 

[Jdfern]

Carefully look at all the vacuum hoses and fittings, a tiny leak can cause a rough idle.