Was hoping someone with more mechanical experience than me could respond to the following question. I had my local mechanic replace the timing belt on my 2001 RX300 yesterday. Mileage showing was 93,000. He is usually very good and I used genuine Aisin timing belt kit. After putting everything back together and firing up engine. We noticed a slight vibration in the engine while running. I know he was very careful when aligning the belt marks. At any rate, the check engine lights eventually came on with codes P1310 and PO303 indicating a problem with ignition coil #3. My question is this: Is it possible that the timing could be off and this code is the result? Had no issues with the car before we did the timing belt change so it seems awfully coincidental that I suddenly have problems with ignition coil #3. Thanks for anyone who can offer advice.

 

Absolutely timing can possibly be off. Take it back to your mechanic for another visual inspection, the belt may have jumped a few teeth when releasing the tensioner. Did you compress your old tensioner or use a new one?

 

I would suggest that swap ignition coil 3 with 1 or 5. They are at the back so it will be bit of pain. While at to check plug #3 as well. I would expect other codes for ignition timing being off. The plugs needs to be replaced at 110K and only use OEM

Salim

 

Thanks to both responses so far. I most certainly will have timing marks rechecked. Yes, a new tensioner was installed. I have already ordered three Denso ignition coils and Denso Iridium plugs. Plan to replace all three back coils and plugs since the plenum has to be removed to access these. Will update this thread when I learn more and get the timing rechecked.

 

Plugs and coils can be changed without removing the plenum. Bit hard m but can be done. I would avoid removing the plenum as the gaskets have to be replaced. [some dont, but I follow the recommendations in the service manual]

Salim

 

Looking like it will be Saturday before I can get the timing belt checked. I am going to ask what I hope is not the obvious, but can anyone tell me what steps/procedure you would follow if indeed the belt has slipped and is not aligned properly. Is it necessary to remove the belt and tensioner to correct this? Or can it be repositioned without reversing all the steps followed to install it? Again, I am completely reliant on my mechanic for this, but would like to know what may be involved in resolving this if indeed it does turn out to be off a couple of teeth. Thanks for all the feedback.

 

The tensioner has to be removed to get enough slack to move over teeth of any gear.

I would start by examining if any gear is off, before even loosening the tensioner.

Salim

 

Thank you.

 

I am posting this followup to my earlier concerns about the above codes showing after doing a timing belt change. I had my mechanic come by today to recheck the alignment of the timing belt and lo and behold, the belt was off by three (3) clicks on the back most mark. The tensioner was removed and reset, the belt moved to the proper marks, and everything was buttoned back up. I was hopeful that I would not see the codes after this, but unfortunately they were still there. So, as a precaution for such an eventuality I had previously ordered 3 coil packs and 3 Denso plugs to install on the backside where cylinder 3 sits. It may indeed be possible to install new coils and plugs without removing the plenum, but neither I nor my mechanic could see any simple way to do that. So the plenum came off and that in itself is a major PIA. My mechanic was able to remove all but one bolt securing the plenum. Enough play was achieved that he could lift up the plenum enough to access the coils and plugs. Afterwards, we fired Ole Bessie up and she purred like a kitten. I will do the front 3 cylinders myself later on. He recommended I get new valve cover gaskets and tube seals for later as well as there appeared to be quite a bit of oil on the coils when they were removed. I know my experience is probably not particularly helpful to anyone else, but I wanted to share it anyway. Thanks to the suggestions I received from others in this forum.

 

Glad you were able to address the codes and your mechanic was able to confirm and reset the timing. I'm curious which bolt he had a problem getting to for plenum removal. Optimally, if he were remove the plenum, it would be the ideal time to change the valve cover gasket and seals. Agreed that removal of the plenum can be a PIA, for the first time i removed the plenum, some of the securing bolts were in tight spaces...it took a while to figure out easier methods for removal.

 

I don't know what was holding the plenum. He said it was a bolt behind the plenum and he had his hand and wrench up against the firewall. I watched a You Tube video yesterday of plenum removal and I could not see any blots in the rear that had to be removed. It may have been something else. Since I was not doing the work myself, I cannot comment further. I totally agree that ideally the valve cover gaskets and tube seals should have been changed while the plenum was off. I offered to run to a parts shop to purchase these, but my mechanic wanted to put this off until another day. I think he was just tired. At any rate, he only wanted $50 for going back into the timing belt and removing the plenum to install the coils and plugs for the back cylinders. I think he felt bad that the timing was off since he felt like he had checked it repeatedly on the first install. I paid $175 for the first job, but didn't want to stiff him with $50 for the second trip out, so I gave him $100. Still very reasonable in my opinion. He's a good mechanic but anyone can make a mistake and I don't think it reflects poorly on him.

 

I think the bolt to which he is referring connects the lifting hook to both the engine block and the plenum. Yes, it is very hard to get to.

 

I wouldn't call your mechanic's job a mistake. Sometimes you just need to step back and get a fresh head to retackle the problem. His rate is very reasonable. There are two vertical brackets that hold the plenum in place that are very close to the firewall . A tip is to loosen the brackets from the bottom so the plenum can tilt forward and give the little space needed to loosen the securing top bracket bolts and two grounds.

 

Thanks Fastnoypi for the tips on removing plenum. Will definitely follow your advice when it comes time to remove it to replace valve cover gasket and tube seals.

 

There are step by step DIY instructions on how to remove the plenum ... check the Knock sensor DIY.

Salim