Cam timing off???

CobraSam

Active Member
Established Member
Joined
Apr 26, 2020
Messages
287
Location
Mass
So I’m new to Mod Motors. Just did a engine/head rebuild. My car is not running correctly and sounds like it’s missing at idle. I will perform all the basic diagnostic tests, but have been thinking....could we have messed up with the timing gears? Like one is a tooth off? Or something along those lines? I’m not getting any CEL to go off of. All my monitors are ready, but no codes. It sounds like a misfire, but so far everything ignition wise checks out fine. First time with mod motors, coming from many years of foxbodys. Gonna start fully diagnosing on Thursday. Thanks
 

CobraSam

Active Member
Established Member
Joined
Apr 26, 2020
Messages
287
Location
Mass
Can you post up a video? Also do you have the ability to datalog?

Sent from my Pixel 2 XL using Tapatalk
Yes I can, either later today or tomorrow. Yes I do have the ability to datalog. It would be through the SCT X4 and their LiveWire program. Which I’m only Ok at using. However, my friend does have a full auto shop with just about every and any thing I believe we will need. It’s going there Thursday. I’m just impatient and am curious what other knowledgeable people have to say. Thanks
Sam
 

03cobra#2

Hobbyist Of Many Hobbies
Established Member
Joined
Feb 9, 2007
Messages
1,257
Location
Cleveland, Ohio
Yes I can, either later today or tomorrow. Yes I do have the ability to datalog. It would be through the SCT X4 and their LiveWire program. Which I’m only Ok at using. However, my friend does have a full auto shop with just about every and any thing I believe we will need. It’s going there Thursday. I’m just impatient and am curious what other knowledgeable people have to say. Thanks
Sam
Reason I ask about datalog is you can log the stft's so see what's going on bank to bank. If you are off a link on the chain I would think is would run pretty bad.

Sent from my Pixel 2 XL using Tapatalk
 

03' White Snake

Well-Known Member
Established Member
Joined
Feb 5, 2007
Messages
3,091
Location
Mass
You cannot be a tooth off, you would be smashing valves. If you have adjustable cam gears, then yes it could be off.
 

CobraSam

Active Member
Established Member
Joined
Apr 26, 2020
Messages
287
Location
Mass
You cannot be a tooth off, you would be smashing valves. If you have adjustable cam gears, then yes it could be off.
Ok this is what I thought. So it’s black or white? Either they’re installed correctly or I’m trashing something?? No adjustable cam gears. So basically, it’s either setup correctly or it isn’t. In that case I would know if it was wrong and I would already be screwed because my pistons and valves decided to get into a bar brawl?
 

hotcobra03

Well-Known Member
Established Member
Joined
Mar 11, 2007
Messages
7,018
Location
poteet,texas
Why a rebuild?

Had mine apart a couple times

1st timer also.

Instructions may confuse some

Looking at engine it say right side set at 11 o’clock.

Which is really passenger side and to us is the left side.

Seen it done on a 2 valve backwards and it ran but like crap

Issues I had after heads.

O2 sensor wet with antifreeze bad

Stretched wire on cam sensor connection po340
 

CobraSam

Active Member
Established Member
Joined
Apr 26, 2020
Messages
287
Location
Mass
Why a rebuild?

Had mine apart a couple times

1st timer also.

Instructions may confuse some

Looking at engine it say right side set at 11 o’clock.

Which is really passenger side and to us is the left side.

Seen it done on a 2 valve backwards and it ran but like crap

Issues I had after heads.

O2 sensor wet with antifreeze bad

Stretched wire on cam sensor connection po340

I bought the car knowing it had bad valve seats and guides at the least. After looking at the shortblock sitting alone in the engine bay, it became obvious that this would be a great time to pull it out and have it rebuilt. So we did, which was a good idea. Car fires right up, and runs. Mechanically sounds just fine. not getting any CEL as of now. We will figure it out for sure. We’ll have to look at the live data and see what the car is doing as far as o2 and fuel trims, MAF and all that.
 

CobraSam

Active Member
Established Member
Joined
Apr 26, 2020
Messages
287
Location
Mass
Why a rebuild?

Had mine apart a couple times

1st timer also.

Instructions may confuse some

Looking at engine it say right side set at 11 o’clock.

Which is really passenger side and to us is the left side.

Seen it done on a 2 valve backwards and it ran but like crap

Issues I had after heads.

O2 sensor wet with antifreeze bad

Stretched wire on cam sensor connection po340

I’m not getting any CEL. Which is strange. My O2 sensors don’t seem to be acting right. I monitored my truck then compared how they were acting to my Cobra. The Cobra o2’s are not oscillating like my truck. Bank 1 stays over 1.1v and bank 2 stays above .500. My short tirm fuel trims oscillate right around 0. I’m wondering if my o2 sensors are contaminated from when the car wasn’t running correctly before and/or from the rebuild. I’m learning how to read data logs and fuel trims, so bare with me.
 

03cobra#2

Hobbyist Of Many Hobbies
Established Member
Joined
Feb 9, 2007
Messages
1,257
Location
Cleveland, Ohio
Make sure you are entering closed loop. Once in closed loop you will see stft's bounce around to keep you right around 1.0 lambda. Probably not a bad idea to pick up a wideband so you can see actual A/F.

Sent from my Pixel 2 XL using Tapatalk
 

CobraSam

Active Member
Established Member
Joined
Apr 26, 2020
Messages
287
Location
Mass
Make sure you are entering closed loop. Once in closed loop you will see stft's bounce around to keep you right around 1.0 lambda. Probably not a bad idea to pick up a wideband so you can see actual A/F.

Sent from my Pixel 2 XL using Tapatalk

Ok, thank you. I have confirmed it does go into closed loop. I do have a wideband gauge installed and am currently troubleshooting that as well. Another AEM UEGO Gauge issue. But I’ll have that figured out. Based on how the o2’s are reading, I’m wondering if they got contaminated like a member had mentioned. I have 2 new Motorcraft OEM sensors and am going to try them out and see how they read. I’m trying to post videos, but it’s not letting me.
 

03cobra#2

Hobbyist Of Many Hobbies
Established Member
Joined
Feb 9, 2007
Messages
1,257
Location
Cleveland, Ohio
Ok, thank you. I have confirmed it does go into closed loop. I do have a wideband gauge installed and am currently troubleshooting that as well. Another AEM UEGO Gauge issue. But I’ll have that figured out. Based on how the o2’s are reading, I’m wondering if they got contaminated like a member had mentioned. I have 2 new Motorcraft OEM sensors and am going to try them out and see how they read. I’m trying to post videos, but it’s not letting me.
Doubt they would get contaminated but you never know.

Sent from my Pixel 2 XL using Tapatalk
 

CobraSam

Active Member
Established Member
Joined
Apr 26, 2020
Messages
287
Location
Mass
Doubt they would get contaminated but you never know.

Sent from my Pixel 2 XL using Tapatalk


Damn!! I was hoping for an easy fix. Well can’t hurt to have 2 fresh sensors in there I suppose. Time will tell. I’m trying not to just throw parts at it and actually diagnose things. Back to it I guess
 

hotcobra03

Well-Known Member
Established Member
Joined
Mar 11, 2007
Messages
7,018
Location
poteet,texas
I had o2 codes instantly.

I used fords pin point test to trouble shoot.

Pcm is very smart. Reading what it’s saying and understanding is the hard part.
 

CobraSam

Active Member
Established Member
Joined
Apr 26, 2020
Messages
287
Location
Mass
I took the front timing cover off to find a new OEM metal chain tensioner was seized and it was throwing the timing off.(my diagnosis). I can’t say for 100% this was causing my issue, but it was definitely not operating as it should be. And couldn’t have been good for my valve timing either way. I also replaced the crank and cam position sensors while I was at it. Either way, nothing like having to tear down 1/2 an engine we just put back together. F*ck me! Car runs great now, like it should for a brand new rebuild. Thanks guys.
 

cj428mach

Well-Known Member
Established Member
Joined
Sep 21, 2012
Messages
7,391
Location
Kansas
Has it ran long? I had a buddy that kept having his 4v begin ticking and having issues with the tensioners not long after install. What he found was that the guy that built the heads put a plug in the head behind the tensioner and it wasn't getting any oil. He was running ratchet tensioners and the ratchet would fail shortly over time after assembly without the oil to help hold it in place. Hopefully you don't have a similar issue and it was just a bad tensioner and not an oiling issue.
 

hotcobra03

Well-Known Member
Established Member
Joined
Mar 11, 2007
Messages
7,018
Location
poteet,texas
Thanks for update. Most don’t.

Something now to add to list of things


Pulling that cover in car isn’t fun. Done it.
 

CobraSam

Active Member
Established Member
Joined
Apr 26, 2020
Messages
287
Location
Mass
Thanks for the interest guys.
Cj428mach, I will absolutely keep this in mind. Thank you. That would be a tough one to catch for sure.
No, it hasn’t ran long at all, so I’m still not 100% it’s fixed. Although, when it happened the first time, then problem was apparent pretty much immediately. Another thing with mine is that 1 tensioner appears to be in proper working condition. Only the driver side was bad. So I had a direct comparison between a properly functioning one and a faulty one. Also the same side as the cam position sensor. I will update further.
 

Users who are viewing this thread



Top