P0340.....help

So we replaced the CPS today (easy enough job if you have small hands around) but the truck is still throwing P0340 code and feels like timing is retarded. Daughter put all new spark plugs and we cleaned throttle body while we had it off to change the cam position sensor. What else should be looked at?

2001 2.7l

 

Ok so took truck to a shop in town. Put oscilloscope on cps and ecm and found that there are no drop outs but show a variance between crank position sensor and cps so suspect either timing chain failure or crankshaft position sensor. Has anyone changed a 2.7l crankshaft position sensor and if so did they have to remove hvac?

 

The timing chains in these 2.7s are stout, i wouldn't suspect that at all

 

I wish I could post the report...shows good signal from crankshaft position sensor and signal for the camshaft position sensor however they are not in sync. Def a timing issue so is there something else that would fail causing this issue?

 

If the cam gears are keyed I suppose you could have something going on up there... remove the valve cover and investigate.... like someone else mentioned, those timing chains very rarely fail

 

Ok so just so I have an attack plan...if the gears are keyed and the chains are stout, but the timing is still off. Could it be the chain was installed incorrectly during a "rebuild " which the previous owner claimed to have done? And I could just adjust the chain position at that point and button back up? Or does front cover require removal to adjust the chain position on the cam gears?

 

Hmmm interesting


Could you take a cell phone picture of the report and post it that way? These timing chains are supposed to last the "lifetime" of the engine. I can personally attest to the fact I rebuilt a 2.7 because the previous owner starved the top end of oil bad enough to wallow out the oil pump housing. I woulda reused that old chain if I hadn'talready bought a new one, it cleaned up just like new.


What brand of CPS did you use? I've seen alot of issues with non OEM sensors. I wouldn't go and buy it from the dealer... Denso is who made em so use the Denso brand one if you haven't

 

Ok i uploaded the diagnostics..

 

It wouldn’t run iff that far out. There is an automatic tensioner in there and even if it was completely worn out you wouldn’t know it, well besides the slap

 

The sensor replaced (camshaft sensor under throttle body) was replaced with a crappy duralast from local autozone (kid purchased) i would gladly throw another one in to rule that out but maybe the crankshaft position sensor is reporting off??? Anyone can look at report and let me know. As mechanically inclined as I am my head isn't on straight with this truck...

 

why would they need to mirror each other in the first place? It’s not engineered by NASA. The guy who suggested buying Denso is 100% correct. If you put Autozone or EBAY crap in there, start over and report back

 

If the previous owner said they did a rebuild.. did they perform it or take it to a shop? When retiming the 2 camshafts the exhaust cam shaft timing gear has a subgear that is spring tensioned and needs a preload.. also the timing chain itself has a mark on one of the links that has to match up with the front mark on the front timing chain that goes around the intake camshaft timing gear.

It's possible those steps weren't done but I don't know what effect that would have. Regretfully I'm only a small engine technician so I have no way of knowing why those waveforms are outta synch but I do know I've read alot of posts on here from other members that have chased electrical gremlins because of non denso sensors. I would start with that if it were my truck

 

Giving me more hope. I will get good sensors from napa or toyota and report back.

 

The crankshaft position sensor is underneath the the water pump outlet on the front.. it's a pain in the D hole. If I remember correctly you got take the alternator out to get to it.

I would start with just the camshaft one first since you know that's a duralast brand one

 

Ok so new Denso sensor..no change. Should I even try the crankshaft sensor? The mechanic said when I picked up truck that the chain was stretched. The motor runs fine , no power but runs. Don't hear any sound from timing chain area. P0340 is still present, the wiring all checks out.

 

Ok we are gonna change the crankshaft position sensor Monday and report back here.

 

I have heard of aftermarket parts... sprockets causing this exact problem... I wonder if the head was replaced with an aftermarket head assembly. It has been too long since I tinkered on a 2.7 so I am not 100% sure if the cam sensor picks up its position from the cam or the sprocket.

 

I wouldn't think that to be his problem, the 2.7 cam sensor is on the side of the head under the throttle body and reads from the cam.. when I rebuilt my engine I used a complete assembly aftermarket chinesium head and other than the exhaust cam being one tooth outta time I had no issue.. then again I reused the old sensor off my original engine.

OP sorry I can't offer more advice, wish I could point you in a better direction

 

I just don’t see anyone getting hung up on the waves matching up on the scope. They are chain driven, you would naturally see some deviation. I assume Toyota just wanted verification that they are both turning. In full disclosure, I am NOT a Toyota technician. And I imagine most first gen techs are retired or nearing retirement. These new factory trained guys aren’t getting trained on our old junk, we collectively as a group are way smahter them them meatheads