[Solved] P0305? A340F Slipping?

Driving home from work yesterday, cruise set about 61mph. Going up a hill that the cruise usually has no trouble with, when it decides to downshift into 3rd till the crest, then it returns. I didn’t think much of it. Little further down the road I come upon a school bus doing around 45, I look left to pass, then accelerate. Truck took FOREVER to get from 50 to 65. Then it drove fine the rest of the way home.

This afternoon I got on the interstate cruise set at 78. I go over a tall flyover with the cruise still set and it downshifts into 3rd again. I’ve been over this same flyover cruised at 65 and it had no problems. Next hill I got to I clicked the O/D off button and truck didn’t bog down or anything going over(78mph in 3rd)(cruise off)

Thinking about putting some Lucas transmission stop slip in cause I’m not really in a good spot to rebuild it right now.

But if i did, what would be the best path to take, rebuild? Reman? New?

Buddy of mine said it could be the trans filter, I just drained and filled the fluid less than 15k ago, but didn’t do the filter. I checked the fluid and the level and color are both correct, and it dosent smell.
219,XXX and original trans as far as I know

Any ideas or thoughts help

 

Check fluid level first. It’s not the filter.

 

If it’s really a tranny issue you could go either one of two paths. One is to upgrade to a 2003-2004 tranny with a stronger overdrive gear or perform a rebuild with IPT transmissions. I’ve heard good things about them on the past. Supposedly better performing parts.

 

Fluid level and color are correct

 

Did you check this by using the procedure in the FSM?

 

Checked it after driving for ~30m while running in park

 

You should run through the full range as described and recheck.

 

Your description makes it seem more like an engine issue than a transmission issue. When you went to pass the school bus, did the transmission downshift? Did the engine revs climb?

 

level is here

 

No, it didn’t downshift, but I didn’t really press the gas that hard. In 1,2,3rd gears it drives fine and feels normal

 

Looks like you're nearly 1 qt low

 

At least.

Just to confirm this is idling at operating temperature after manually shifting through the range?

 

That would temporarily help if the frictions are gone.

 

Yes

 

Put a half a quart of dex 3 in it and drove home from work, everything seemed back to normal. Got almost back home and was driving up a hill at about 60 no cruise, and it wasn’t slipping, felt fine. Then the check engine light started flashing. Before I got to the driveway the light went off. Got to the garage and the stored code was P0305 (Cylinder 5 misfire detected). Went and re-created the scenario I just did, same result. Cel came on going up the hill and went away after. Tried again with the O/D off and the light never came on, but the motor bogged slightly. (I cleared the code before each attempt). Pulled #5 spark plug and ignition coil they both look fine, both are less than 10k old.
What the hell is going on?

 

To me it sounds like a fuel delivery problem if it’s level related. A bad coil wouldn’t care if your level or not.

Not sure if you have Denso coils (OEM) or not but aftermarket ones can exhibit issues after a year or two. Truthfully I don’t think it’s the coils myself.

 

I have the TRQ performance coils in there
Installed October 28 2023

I did all the spark plugs and coils at once and saved 1 of each. Should I try swapping them with the old ones to test?

 

I have those in mine as well. Already have 3 bad after 25k miles and 4 years later. Of the 3, one went bad within a week.

I’d probably check fuel pressure in the rail, both level and on an incline.

 

I’ll go rent a fuel pressure gauge from oreilly tomorrow

 

Make sure you have a banjo bolt to schrader valve adapter.

 

Fuel pressure is 43psi on flat ground and on a hill
Checked compression on Cyl 5 it’s about 161lbs
Checked Cyl 3 for reference too it’s about 176

 

You checked the fuel pressure for both the conditions listed below according to the FSM (SF-7 to SF-8 section)?:
1. Engine off but ignition ON
2. Engine running at idle

According to my 2002 V8 FSM spec (similar to 2003), it's 38-44 psi for step #1 and 21+ psi for step #2. If both are good, I'm not sure where to go at this point. I'll think about it, maybe someone else can chime in here.

 

I checked the fuel pressure while it was running (idling), both on level ground and on an incline.
43psi both times.
I just switched the coils on cyl 3 and 5, gonna drive home and see if there’s a change or if I get another code

 

This thread is getting kind of long so here’s a list of the issues I’m having and the things I’ve already checked:

Issues:
All of these started 2-3 days ago

#1 Low power at interstate speed in overdrive, on cruise it downshifts climbing some hills (70-80 mph)

#2 Intermittent P0305 that went away and I cannot get it to come back when replicating the conditions, (trying to hold 60 going up a long steep hill in o/d)

#3 Downshifting in cruise on hills it usually has no trouble with, at the same speed I usually go

Tests and checks I’ve run:

Trans fluid level and color are good

Oil level is good and fresh

Coolant level and color is good

Spark plugs are 7 months old and look to be in good shape (ngk ruthenium)

Ignition coils are also 7 months old and i didn’t get a code for #3 cyl when I switched #3 and #5
(TRQ performance coils)

Fuel pressure is 43psi on level ground and on a hill

Cyl 5 compression is 161lbs and cyl 3 is 176

Fuel mpg hasn’t changed from normal

Normal driving on country roads feels normal in all gears (0-65mph) truck takes off like it usually does and shifts smoothly

Coolant temp is steady at 190F like normal

Other pertinent info:

Short tube headers were installed 2 weeks ago

Fuel injectors were changed at the same time as the plugs and coils (upgraded to 12 hole)

219,XXX miles

Engine load pct% goes from ~50% to around 75% when cruising up a hill at interstate speed

Trans fluid was somewhat low so I added half a quart and the downshifting problem got slightly better

Any suggestions or ideas help, thanks

 

Cardinal sin. Never aftermarket on this part. Talk to @Jack McCarthy about that. But he’s not the only one. People have even had problems with big name brands like MSD. Bad l, random-misfiring, or underperforming coil will cause many symptoms you listed.

 

Oh and looks like you can ask @jerryallday also. https://www.tundras.com/threads/ignition-coils-which-one-would-you-pick.143313/#post-3601883

Your issue may be your coils/ignition not being hot enough/functional.

 

That may be the case but wouldn’t that make the problem rpm-based instead of speed based? Or does it have to do with the engine load?

The reason I replaced them to begin with is because 3-4 were cracked down the seams and the insides were showing. I saved the best looking one as a spare. I’ll switch #3 coil back to #3 cyl and put the old one in #5 to see if anything changes

 

I second, or maybe third the coils. Folks like to tinker and mod things. I get it. But the hot air intake, the TRQ coils and possibly the 12 holes could all be contributing to the problem. Coils are most suspicious for this current problem though.

 

I’m tempted to get my oem injectors cleaned and tested, and pull the 12 holers