Making Progress, but still very rough under load. Idle good.

[NC Tom]

For anyone who may be following this thread.

 

I've gone back checked the throttle body, and it's clean. The firing order is correct. I have spark, I have fuel pressure and delivery, enough for a decent idle. Open the throttle and it sounds like an out of tune Harley. I have not tried to drive it. Is it possible that during the changing of the tank and fuel pump, something got into the system? If so, would it only affect fuel delivery under load and not idle?

I have been trying to follow the advice given here, but it seems like everything checks out positive. I'm grasping for straws here before I get it towed to a garage. LAST RESORT.

[ratrapp]

if you get it towed to somebody please tell them exactly what you've done andvwhat you've replaced.it will help them.we have to interrorgate customers to pull the truth out of them.

[NC Tom]

5 hours ago, ratrapp said:

if you get it towed to somebody please tell them exactly what you've done and what you've replaced.it will help them.we have to interrorgate customers to pull the truth out of them.

No offense to you. You're kidding, right? All they do is nod and then do their own thing anyway. Charge for parts you already replaced plus labor you already did yourself. Personally, my interactions with so-called professionals has been less than good. I've worked with three different garages in the Boone area. 1. Did good work, but refused to install new parts that I provided. God forbid I save a little money vs them charging more for the same part. 2nd garage did a rear brake job and left a line down that was rubbing against a tire. Rubbed through and I lost ALL braking going down hill! Had to put it in first and when I slowed enough, threw it in park. 3rd garage has been uneven and I just found out they fired half their mechanics for doing poor work. I think my only other option is to get crucified by the local Jeep dealer. Supposedly, they have an older guy there who knows MJ's. I've been in this area for almost 10 years and have never had anyone recommend a garage. They only tell me which ones NOT to go to.

[ratrapp]

well unless hes actually worked on older mjs or xjs the i would avoid a dealership since most of the techs probably there now have never worked on a 4.0.a good garage would like to know what you've done so they know where to look because obviously since you cleaned your injectors it hasnt run right,correct?i own a garage and yes i very rarely install customer parts for several reasons.1st is ususally the customer buys cheap crap off of amazon or ebay that may or may not be good and then they aske me to warranty parts they bought.if i sell someone something all the local stores i deal with stand behind it and usually give me a labor claim.2nd thing is yes most garages do mark up parts to stay in business including myself.i could charge the cost of parts but i would just have to increase my labor rate.

[AZJeff]

On 5/12/2023 at 2:39 PM, NC Tom said:

For anyone who may be following this thread.

 

I've gone back checked the throttle body, and it's clean. The firing order is correct. I have spark, I have fuel pressure and delivery, enough for a decent idle. Open the throttle and it sounds like an out of tune Harley. I have not tried to drive it. Is it possible that during the changing of the tank and fuel pump, something got into the system? If so, would it only affect fuel delivery under load and not idle?

I have been trying to follow the advice given here, but it seems like everything checks out positive. I'm grasping for straws here before I get it towed to a garage. LAST RESORT.

You say you have spark.  How as that verified?  Did you test every plug and every plug wire?  What does the rotor/cap look like?

 

And may I suggest you borrow a vacuum gauge from somewhere and test your idling vacuum.

[NC Tom]

4 hours ago, AZJeff said:

You say you have spark.  How as that verified?  Did you test every plug and every plug wire?  What does the rotor/cap look like?

 

And may I suggest you borrow a vacuum gauge from somewhere and test your idling vacuum.

I have a spark tester and the cap still looks new. A vacuum gauge is on my list of tests. A friend with more experience than I is stopping by tomorrow. Maybe we'll finally figure this thing out.

[NC Tom]

Well, found out I have a manifold leak that was staring me in the face. I imagine if I have one, I have more.

 

@ratrapp what would the cost range for this repair? Can it be done by a noob?

 

 

[ratrapp]

can it be done by a beginner?yes but the only thing that really can be a problem is if the manifold bolts break off.usually its either the very front or very rear bolt that breaks on the exhaust side.the gasket itself is pretty inexpensive but shop time could range between 2-4 hours billable if any bolts break then of course that would be extra.if its only leaking on the exhaust side then that may not effect the running of it.

[NC Tom]

4 hours ago, ratrapp said:

if its only leaking on the exhaust side then that may not effect the running of it.

That's interesting because the members here are always talking about "tighten your manifold bolts". If loose bolts can cause a running problem, why wouldn't an actual leak cause a problem?

 

My next step is to clean the heck out of the TB. Apparently, I haven't been deep cleaning it. Just wiping it out.

[ratrapp]

if the bolts loosen on the intake side then yes it can cause running problems.exhaut leaks close to the o2 sensor can cause probelms as well.cleaning the tb will only affect idle.it has no effect whatsoever as far as the actually running.if it carbons up on the blades or the sides it can affect idle or cause a sticky throttle but thats it.its not like the newer vehicles with electric throttle control.a bad tps can cause running problems but cleaning the tb itself won't.just like your iac valve it only controls idle functions like cold start up,a/c kicking on etc.

[AZJeff]

22 hours ago, ratrapp said:

if the bolts loosen on the intake side then yes it can cause running problems.exhaut leaks close to the o2 sensor can cause probelms as well.cleaning the tb will only affect idle.it has no effect whatsoever as far as the actually running.if it carbons up on the blades or the sides it can affect idle or cause a sticky throttle but thats it.its not like the newer vehicles with electric throttle control.a bad tps can cause running problems but cleaning the tb itself won't.just like your iac valve it only controls idle functions like cold start up,a/c kicking on etc.

Punctuation would make this easier to read/understand.

 

Let's start with what the manifold leaks can do:

1.  leaks on the intake ports will confuse the MAP sensor, and that will mess up mixture.

2. leaks on the exhaust ports will cause the cat. converter to get erroneous combustion mixture, and send erroneous information to the PCM.

 

The manifold gasket design on the 4.0 is prone to leakage.  I recommend you spend the money on a "Remflex" gasket, as it compensates for the issues the OEM design fails to do.

 

There are three bolts that are used on the 4.0 that hold ONLY the exhaust manifold.  There is one at each end of the head, and one in the center at the top near the throttle body.   ALL the other bolts due a shared job of holding both the intake and the exhaust manifold onto the head, using special conical washers.   This means you can remove all of those bolts and take off the intake by itself, and then focus on removing the three exh. manifold bolts separately.  This is important because the frontmost and rearmost of the manifold bolts can be tough to get out.  (They are actually nuts on studs, BTW.)

 

To address these, you will want toSOAK those two nuts with a bunch of penetrating oil before you try to remove them.

 

PRO TIP:  I find trying to line up the bolts with the conical washers on them when reinstalling the intake manifold to be a HUGE exercise in frustration.   I replaced all those bolts with studs and nuts (and reused the conical washers.)

 

A helper to align the manifold when installing them make the job easier, so offer your buddies some pizza when it comes time to put it back together.

[NC Tom]

1 hour ago, AZJeff said:

 

That, my friend, is great info and I thank you. Now, what time will you be coming, and what do you want on your pizza? 

[AZJeff]

17 hours ago, NC Tom said:

That, my friend, is great info and I thank you. Now, what time will you be coming, and what do you want on your pizza? 

If you lived in AZ, I would be glad to help.  NC is a bit far away for a quick road trip.

[NC Tom]

On 5/17/2023 at 10:41 AM, AZJeff said:

If you lived in AZ, I would be glad to help.  NC is a bit far away for a quick road trip.

 

I'm starting this project today. I decided to go with a Fel-pro gasket. Hopefully it will last for a long as I have the truck.