Hi there all,

Got an 03 Linc Navi with 155K 5.4L and I think the tranny would be the 4R100?

Starting to slip a bit, not 1st or 2nd or even 3rd that much, but OD is an issue esp on the Hwy when I'm trying to pull a hill, it's jumping a bit... if I turn off OD on the shifter 3rd is ok, but will also slip a little...

Checked the stick - said it was low - added about 1/2 a quart which brought it up to the fill cold area but the truck was running for 5 mins prior... still doing this after 1/2 a quart - should I put more in until it's just below the Overfill mark?

I checked it in park on a level surface...

My question is, is it just low on fluid or could there be another problem? - the RPM's stay the same when it it chattering... but the check engine light flashed once on me when this was happening - (the yellow engine icon) - it's not currently on...

 

In order to fix this you MUST read the codes that are stored in the PCM. Forscan is a great way to do it.You can download Forscan at www.forscan.org.

The places that read codes free can't read all of the codes.

When you checked the trans fluid was the engine running?

 

You start your message by saying the tranny is slipping, but finish your message by saying the RPMs stay the same when it is chattering and the check engine light flashes. You're describing two different things. The latter description is commonly an engine misfire. Checking for codes as Mark recommends would help identify that.

If your tranny is slipping, then the RPMs will noticeably increase with increased throttle but you're speed won't increase proportionately. It's that what's happening?

 

Hi There - Yes, I checked it with the engine running. Figured that would be the best way since the pump is running and would tell me where the level is when it's working seeing what is left in the pan. I added about 1/2 a quart - which then brought it up to the cold area from LOW but perhaps it still needs more? it's not in the Full Hot area at all... I wonder if OD requires the most fluid and it's a bit too low still?

If I drive like an old man, it's not that noticeable, but if I try to pull a hill in OD and give her gas, she will buck a little bit - not violent, but enough where you notice it for sure. If I downshift into 3rd, (turn off OD) it revs up of course and seems ok, but if I hit the gas harder there even in 3rd gear, sometimes it does it too but not as bad as when it's in Lock up.

When I said the CEL flashes on and off it only did that once when I was being on it hard, it doesn't flash on and off continuously like a misfire - I thought it throws something like that because there could be a sensor in the tranny too. It's not on now at all - so not even sure if a code is stored still? - I have an Autel scanner that does airbags and all... guess I should see if it has any stored codes.

My questions are: - would an older filter be causing a flow problem? - it has 160K on her - and I don't think I ever had the filter changed... the fluid looks good - nice and red - no burnt smell, and it looks the same on the stick as new fluid.

If I added one of those Tranny in a bottle things - (leaning towards the Lucas one, any others you like better?) - will that help with this?, make it worse?, or ruin the tranny completely? - also, lets say I add that and I end up needing an overhaul - is adding that stuff gonna make the overhaul harder to do? or does it matter?

I just want the right course of action here for the safest play - It's not a daily driver, but it does need to be 100% for when I do need it.

 

I think you're describing a misfire that hasn't fully set a misfire check engine light. Hook up the scanner and fingers crossed there is a pending code that can be read. If your scanner reads and outputs live data including fuel trim, that could be helpful as well. Too lean or too rich could cause a misfire, but then the question becomes why is it too lean or too rich? Intake leak, exhaust leak, bad O2 sensor, clogged fuel injector? Maybe fuel trim is good, but you have a coil going bad?

Good luck. Occasional random issues like this can be a nightmare to solve.

 

It's not a random issue - it is 100% repeatable, but I will see if I can pull a code. Could be that, and I don't want to rule it out.

I had this happen to me with my wifes old 93 chevy lumina and it was a bad coil pack, and you would have thought it was the tranny. So yeah, I hear ya on a misfire.

The question is, if it was the tranny acting up, would it throw a code? or only time I would see the CEL is if there was an issue with the engine unrelated to the tranny?

 

At least it's repeatable so it's easy to check if the issue remains after you change something.

I believe there are some tranny fault codes that trip the check engine light, but I can't say for certain. I might be thinking of a different model year. Also, I believe it would only light up if there's an electrical/sensor issue, not if there's a mechanical issue.

 

If you have never changed the filter, have you ever changed the spark plugs?

 

The check engine light can illuminate for certain transmission problems, and they don't have to be electrical problems.

 

I figured you'd have the answer!

 

Hi guys,

Anybody have good or bad experiences with the Lucas Tranny fix? - My thought is that even if the tranny is not the issue, will it do any harm and just keep things better? I don;t mind wasting 13 bucks but I don't want it to do anything worse if the tranny wasn't the issue in the first place. People claim it's good as an additive for improved performance and lowers heat etc - but hype vs reality would be great!

Im thinking I should just do all new plugs and coil packs - even if that doesn't fix the problem, they have never been done and it has 160K Wires too?

If I didn't use Motorcraft, what is another good brand to go with esp for the coils? or do I not want to screw with non OEM for that? - I know like my wifes Toyota really hates after market stuff... I would think Motorcraft plugs are not that much more so that's a no brainer... but a set of 8 for coils can get pricey. I plan on keeping the truck.

 

Wuuuuut? Never changed plugs? Def do that #1! Plugs must be Motorcraft. Coils - I bought a set of 8 off eBay many years ago; 1 went bad, they never gave me a new 1 under their "warranty" so I just bought a new 1 from Autozone. No issues since. I did change the boots and springs when I did a new intake manifold 2 years ago, but I did that for convenience and deteriorating rubber from intake leak.

Again, I think your issue is a misfire, and new plugs and coils (or coil boots and springs, because that's generally cheaper) will make an improvement.

 

Ok, are they pre gapped usually? - what is the correct for a 5.4L 2003? .044? when you said coil boots and springs, I only see one thing for the coils - round top with a tube.. is that the whole assembly? I do they just pop off? does the cover hold them in place? - Thanks for the help - I will start there for sure! - PIA to get the covers off though - do you know the socket size by chance for the plugs? 5/8s? I know I want one with the rubber insert. Looks like a few extensions and swivel are gonna be needed.

Any tips would be great - looks like I need to remove the PS res too... fun fun...

 

Motorcraft plugs SP493, usually they're pre-gapped at .054 but always double check. Search Google for a 5/8" magnetic spark plug swivel socket, they're under $15 and way better than the rubber, and you're local auto parts will have them too. Coils are held down with 1 bolt, I think it's a 7mm. Denso is OE if you don't mind spending a little extra (check RockAuto), or you can get a set of 8 on ebay for cheap. Coils are complete with spring and boot.

What worked for me was to have all plugs gap checked and ready on a table with a little bit of anti-seize and all tools ready. Remove all coils, blow any debris from the spark plug wells with compressed air, then remove and replace 1 plug at a time. It's easy, just a little time consuming. My first plug job was almost 3 hours, now I can do it in 45 minutes, and I'm a little **** with my vehicles.

Good luck, I think that will fix your stumbling problem. Been there, done that!

 

Ok, put my reader on her - no codes - neither active or stored.

anyone know how I should be reading the trim data and if that would point to a misfire or is there some other data point I can look at on here as I drive or even at idle?... shows the AT temp too, which I would think would get too hot if it was slipping? and maybe Mark might be able to answer this - how hot is too hot mark? - I can drive it on the HWY and see see where the temp is then?

Other question - I do run 93 oct when it's cheap enough but with the price of gas lately, I can't afford $100 every 5 days, so I have been running 87... should I really only run higher octane in this engine? - can that lead to some of this over time? I think the sticker says 91 on it on the gas lid - so even 89 is out I guess? - seems to run on 87 ok but rougher than 93 for sure.

In anycase Here is what I ordered today:


Figure it's PM anyways - regardless if it fixes my issue or not. Hopefully it's something that simple.

I'm guessing this is a great start - I think I will replace the air filter too actually - I do keep up on oil changes too - and BTW I topped off with actual Motorcraft Merc V in the red bottle in case Mark was reading these :-)

Thanks everyone!