NewCelica.org Forum banner

1 - 20 of 113 Posts

·
Registered
Joined
·
538 Posts
Discussion Starter #1 (Edited)
Car: Stock 1zz, 5 speed

Symptom: Lots of hesitation and lack of power when accelerating, mainly in the 2-3k rpm range. It's most noticeable in 2nd and 3rd gear and during warm weather. I've had this issue for the last few years.

Troubleshooting I've Done: LTFT always within a -7 +7 range during acceleration. To my understanding, this rules out any significant vacuum leaks or fuel delivery issues. Strangely enough, it stays at a steady 0 at idle.

I've also put in a new air filter, new spark plugs, cleaned the IACV & throttle body with Intake cleaner (by actually removing them) and MAF with MAF sensor cleaner.

TPS sensor reads 11% at idle. Looks fine. Throttle stop screw is set so that there is no slack in the throttle cable.

Known problems: CEL code P0505 (most likely bad IACV). Car idles between 1k and 2k rpms. I assume a bad IACV only affects the car during idle. Update: See post 46.

Since fuel trims appear to be okay, I suspect that ignition timing could be off. In my understanding, if timing is too far off, the ecu will pull timing to prevent the motor from knocking, which would also cause a loss of power. Would love to hear any other opinions/thoughts.
 

·
Bring on the 12's...
Joined
·
6,081 Posts
Might be time for new coil packs and plugs. Solved a similar-ish kinda problem for me.
 

·
Registered
Joined
·
1,419 Posts
Might be time for new coil packs and plugs. Solved a similar-ish kinda problem for me.
Similar problem here. From 1-3k I'm getting a lack of power. Was this problem on your 2zz? Would it be beneficial for me to just replace the coils as a form of maintenance and potentially solving this? Not trying to thread jack here, but just curious. No matter what we did on the dyno and tuning, there's just a huge lack of acceleration at this power range.
 

·
Registered
Joined
·
538 Posts
Discussion Starter #5
How many miles are on the motor?
Is the fuel pump original?
Dentman
Motor has 130k on it. As far as I know, it still has the original fuel pump.

Might be time for new coil packs and plugs. Solved a similar-ish kinda problem for me.
I forgot all about that. But I figure if the plugs/coils were bad, I'd be getting a misfire code?
 

·
Registered
Joined
·
538 Posts
Discussion Starter #6
Is there a way to test if the coil packs are good? I know you can test the resistance of plug wires, can something similar be done with coil packs? I couldn't find any info on this.
 

·
Bring on the 12's...
Joined
·
6,081 Posts
I was looking for info on this for aaaages to work out my odd problem in lift, but had no joy. I found a few threads however about 2zz coil packs arcing, which lead me to inspect mine and I took it from there really.

This thread might help bro:
http://www.pistonheads.com/gassing/topic.asp?t=1221852
 

·
Registered
Joined
·
538 Posts
Discussion Starter #8
I was looking for info on this for aaaages to work out my odd problem in lift, but had no joy. I found a few threads however about 2zz coil packs arcing, which lead me to inspect mine and I took it from there really.

This thread might help bro:
http://www.pistonheads.com/gassing/topic.asp?t=1221852
Thanks man. One other thing I noticed, my valve cover gasket is bad. There's a bit of oil in the spark plug wells. Could that be a cause of hesitation?
 

·
Bring on the 12's...
Joined
·
6,081 Posts
No idea how oil would get down the wells... :shrugs: unless you mean on the plug threads/ground strap? Because yes, an oil fouled plug will misfire and be more prone to knock, particularly under load. On my car it got so bad that I ended up pulling loads of ignition timing from my map. Once I'd gotten a strong spark working - I'm now not seeing any oil on the plugs (well, maybe a tiny bit on #4) and I'm able to tune it to run very sharply now without any knock. A strong spark is always cool.

I guess a bad valve cover gasket that leaks air in, could create a vacuum leak and your misfire could just be related to running lean because of this. How's your idle holding up etc?
 

·
Registered
Joined
·
538 Posts
Discussion Starter #10
No idea how oil would get down the wells... :shrugs: unless you mean on the plug threads/ground strap? Because yes, an oil fouled plug will misfire and be more prone to knock, particularly under load. On my car it got so bad that I ended up pulling loads of ignition timing from my map. Once I'd gotten a strong spark working - I'm now not seeing any oil on the plugs (well, maybe a tiny bit on #4) and I'm able to tune it to run very sharply now without any knock. A strong spark is always cool.

I guess a bad valve cover gasket that leaks air in, could create a vacuum leak and your misfire could just be related to running lean because of this. How's your idle holding up etc?
Yeah, I did mean around the plug threads. My idle is sporadic, but it's most likely due to the IACV going bad. When I unplug it, my idle does nothing. I'm starting to think my problem is definitely the oil around the plugs.
 

·
Bring on the 12's...
Joined
·
6,081 Posts
Using OEM heat grade plugs? I found that going back to grade 6 meant less fouling and was able to burn off most of any oily deposits. This combo with new coil packs solved the misfire for me.

Hope you get it sorted :)
 

·
Registered
Joined
·
538 Posts
Discussion Starter #12
So I took off my valve cover today and replaced the gasket. I didn't look at the heat grade of the plugs unfortunately. All I know is that they were the stock OEM spec NGK Iridiums.

Anyway, I took a look at the timing chain and from what I've read on here, it looks way off. My understanding is that the two yellow links should be directly above the notches on both gears. Maybe it's only supposed to be above the notches when you first install it? Can someone provide some input?


 

·
Bring on the 12's...
Joined
·
6,081 Posts
Looks ok from here. The coloured links only really have relevance when u assemble the motor. The chances of you turning the motor to have it at cylinder 1 tdc with the timing dots aligned correctly and those coloured links in sync, are very slim.

The important bit is the 7 links between the two sprockets. However I can't see if you've actually lined the sprockets up correctly :shrugs:
 

·
Registered
Joined
·
538 Posts
Discussion Starter #14
Looks ok from here. The coloured links only really have relevance when u assemble the motor. The chances of you turning the motor to have it at cylinder 1 tdc with the timing dots aligned correctly and those coloured links in sync, are very slim.

The important bit is the 7 links between the two sprockets. However I can't see if you've actually lined the sprockets up correctly :shrugs:
Well that makes me feel better. I've had bad experiences with timing belts in the past, so these things terrify me. By the way, is 7 links on the 2zz? I see only 6 links on mine.

As far as the sprockets go, you're right, it's hard to tell if they're aligned. I should have taken better pictures. I didn't install the chain, so I can only hope the previous owners never messed with it. Thanks for the help Celicasaur. Unfortunately though, I'm still having the hesitation issue. :(
 

·
Bring on the 12's...
Joined
·
6,081 Posts
Let's start with the simple things to diagnose then. First up - pull the plugs and get some clear pics up. Ideally if you have a feeler gauge, you'll post the gaps. If they've been in there for ages, the tip will have worn down and the gap will effectively have been increased. If that's the case, a fresh set of plugs should solve the issue nice and cheap.

I bought a car for the Mrs last week actually and I noticed a very obvious misfire/hesitation at low rpm, particularly under load...I checked the plugs and they were as described above. I changed them and the problem went away :thumbup:
 

·
Registered
Joined
·
224 Posts
Sounds a bit like a bad MAF to me. But I would start at trying to clean the plugs first or change them. Its cheap maintenance anyway.

I would not always get a code for the MAF when it went bad.
 

·
Electromagnetic Wave :-h
Joined
·
15,247 Posts
Throttle stop screw is set so that there is no slack in the throttle cable.
That is not how you adjust the throttle cable slack.

If you messed with the throttle stop screw:



You might also want to check the intake manifold gasket. Seems to be a prevalent 1ZZ issue. However, your LTFTs do look OK.
 

·
Registered
Joined
·
538 Posts
Discussion Starter #19 (Edited)
That is not how you adjust the throttle cable slack.

If you messed with the throttle stop screw:



You might also want to check the intake manifold gasket. Seems to be a prevalent 1ZZ issue. However, your LTFTs do look OK.
I saw that article previously and readjusted the throttle stop screw correctly. I misspoke when I said cable slack.

As for the intake manifold gasket, that was my biggest suspicion for my problem. I even went out and bought the gasket and was ready to put it on. It was right after that that I checked my LTFT's, which checked out fine. I sprayed some intake cleaner around the manifold to where it bolts up to the motor hoping to hear some irregularities, but nothing out of the ordinary happened, so I figured it's not worth the effort to change the gasket right now.

I'll pull my spark plugs and take pictures of them and I'll make sure I have the correct ones in there. I also purchased a new IACV which I will install next week. Hopefully that will help eliminate a variable.
 

·
Electromagnetic Wave :-h
Joined
·
15,247 Posts
What happens after you reset the ECU?

Car idles between 1k and 2k rpms.
Did you adjust cable slack? The throttle should be resting on the stop screw.

Generally speaking, w/o any other codes, the P0505 indicates either too much air passing the throttle plate or air entering past it (such as manifold or vacuum leak).
Might be a weak throttle return spring.

Look at Loop status at idle (when warm). Should be Closed Loop. Where your troubles are just above your idle rpm, I suspect that the faulty high idle may have thrown off the fuel map in that range.
 
1 - 20 of 113 Posts
Top