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MR2zzS - lots of hesitation, unused plug

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3.1K views 31 replies 12 participants last post by  zze86  
Z
#1 ·
Just bought a 2zz-swapped MRS and it has crazy hesitation problems. Will hesitate throughout the powerband but occurs almost religiously at part throttle around 2500-3500 rpms. Almost feels like it's fuel-starved. Sometimes Idle goes crazy and will stall out. But at WOT, it pulls hard, especially once it hits Lift.

CEL comes on for O2 sensors but PO replaced the O2s. It has PPE headers straight to the exhaust so no cat. PO has also replaced the spark plugs and ignition coils trying to figure this out. I thought it was sensor related and put on a cheap scanner. Nothing jumped out to me immediately except the TPS which was reading ~10% at idle but only 70% at WOT.

I am almost certain it is the TPS as the symptoms make sense but wanted to throw this up and hear the experts' opinions. Anything else I should check for?

Here's a pic of wiring for the TPS, which appears to be correct, given the 2zz swap (brown wire moved to outside) EDIT: lol, not sure why the pic is being censored for "sensitive" content. It's a pic of the TPS wiring plug, lol
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Also I was wondering what these wires are for? I am assuming whoever did the swap (not the PO) wired it up themselves and these wires are for Lift.
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Finally, whoever did the swap just kind of left this hanging around. There is an unused grey plug and I wondered if anybody knew what it was for?
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TIA!
 
#3 ·
No. TPS does not cause this kind of problem.

If the TPS were actually reading -10% it would throw a check engine light for sensor out of range, circuit out of range, or other error. Correct range for TPS is from about 10% to about 90%.

Anyway just for arguments' sake, disconnect the TPS from the harness, and post a close-up picture of the wires going into the connector, there is a brown wire, a blue/red wire (some call it purple) and a yellow wire, make sure they are visible. These wires are re-arranged in the harness for the swap, let's see if it was done correctly.

It looks like the EVAP VSV is just swinging in the breeeze. It should have one hose coming into it from a hardline on the firewall from the charcoal canister, and another hose to the intake. If the nipple on the intake is open, because there is no hose going to it, or the hose is not connected to the VSV, you have a massive vacuum leak.

The four-wire connector next to the EVAP VSV is the bank 2 O2 sensor connector. The 2zz has only one O2 sensor, on bank 1, so this connector is not used.

Post a picture of your intake, showing the location of the MAF sensor.

If the lift sensor and OCV were not connected to the ECM, you would have trouble codes aka CEL meaning check engine light for those components disconnected.

Post any codes you have on the scan tool. List the numbers.
 
Z
#4 ·
MerryFrankster said:
No. TPS does not cause this kind of problem.

If the TPS were actually reading -10% it would throw a check engine light for sensor out of range, circuit out of range, or other error. Correct range for TPS is from about 10% to about 90%.
Click to expand...
TPS is only showing 10%-70%. No CEL for the TPS though. So problem? No problem?

MerryFrankster said:
Anyway just for arguments' sake, disconnect the TPS from the harness, and post a close-up picture of the wires going into the connector, there is a brown wire, a blue/red wire (some call it purple) and a yellow wire, make sure they are visible. These wires are re-arranged in the harness for the swap, let's see if it was done correctly.
Click to expand...
I'll try to get a better angle of Pic1. (y)

It looks like the EVAP VSV is just swinging in the breeeze. It should have one hose coming into it from a hardline on the firewall from the charcoal canister, and another hose to the intake. If the nipple on the intake is open, because there is no hose going to it, or the hose is not connected to the VSV, you have a massive vacuum leak.
Click to expand...
I'll double check but, it looked good. Any suggestions on where to mount this thingy?

The four-wire connector next to the EVAP VSV is the bank 2 O2 sensor connector. The 2zz has only one O2 sensor, on bank 1, so this connector is not used.
Click to expand...
(y)

Post a picture of your intake, showing the location of the MAF sensor.
Click to expand...
I'll get one tomorrow when there's more light. (y)

If the lift sensor and OCV were not connected to the ECM, you would have trouble codes aka CEL meaning check engine light for those components disconnected.
Click to expand...
(y)

Post any codes you have on the scan tool. List the numbers.
Click to expand...
There were four. All for the O2 sensors. I'll have to double check the exact code again tomorrow.
 
#5 ·
Check if your cabin carpet is obstructing your gas pedal. Then check that nothing is obstructing the cable to the throttle cam. 10% for the minimum is normal. You should be getting more than 70% for the top end, but after about 50% opening it makes very little difference how far you actually open the throttle - in other words this is not the cause of the problem.

O2 sensor codes have different meanings and they indicate different kinds of problems "O2 sensor codes" without qualification means about the same as "eenie minie moe."

PS> The fueling for your engine is based on the MAF sensor. The ECU takes the MAF sensor measurement and dispenses fuel accordingly. There is some correction made in closed loop i.e. low throttle opening based on O2 feedback. In open loop i.e. there is no O2 sensor feedback. The TPS is used only for acceleration enrichment when push the pedal down rapidly. It does not govern the base fueling of the engine. If you were running ITB's and you had a standalone ECU with a alpha-N tune, this would not be true. The fueling would be based entirely on the throttle position.
 
Z
#9 ·
This sounds like a reasonable culprit. The filter is a bit crushed in the engine bay and is jammed onto the end of the MAF tube so I'm sure there's tons of turbulence going into the MAF.

Intake tube
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Intake tube on bottom, MAF and whatever that thingy is on top
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Intake vacuum line
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Crushed intake
Image
 
Z
#8 · (Edited)
Well I barely had any time tonight. Late work meeting, kids to sports, made spaghetti. Didn't get much of a chance to do anything other than pull the codes and take some pictures in the dark, lol.

CEL has 4 codes, repeats P0135 and P0141 twice.

Here's a pic of the wiring for the O2 sensors
Image


Upstream O2
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downstream O2
Image



Here's the wiring for the TPS
Image
 
#11 ·
Your wiring for the O2 sensors is all wrong.

The upstream sensor plugs in by the timing cover.

The downstream sensor plugs in behind the taillight, where you have labeled "upstream O2."

How is it that you have two photos for "downstream O2" located in different places. In a 2zz, there should be only one upstream O2, and one downstream o2.

This is just going by the labels you put on the pictures. Maybe you meant something else other than what you posted. People often do that.

This is also assuming that you are using a 1zz Spyder engine harness.

Try verify this and fix it first, or your car will never run right.
 
Z
#12 ·
MerryFrankster said:
Your wiring for the O2 sensors is all wrong.

The upstream sensor plugs in by the timing cover.

The downstream sensor plugs in behind the taillight, where you have labeled "upstream O2."
Click to expand...
Oh boy. Neither one is near the timing cover :cry:

How is it that you have two photos for "downstream O2" located in different places. In a 2zz, there should be only one upstream O2, and one downstream o2.

This is just going by the labels you put on the pictures. Maybe you meant something else other than what you posted. People often do that.
Click to expand...
Corrected.

This is also assuming that you are using a 1zz Spyder engine harness.

Try verify this and fix it first, or your car will never run right.
Click to expand...
Unclear at this point. Anyway for me to tell definitively?

Thanks for all the guidance!
 
#13 ·
The guidance is that the thingamajig you have now relabeled as the upstream sensor plugs in by the timing cover. You may need an O2 sensor extender cable to reach the plug, or you may need to purchase a O2 sensor with a longer wire - IDK because I can't really tell how long the wire is from your pictures.

For now, if you do not have enough length on the upstream O2 sensor wire, you can take the downstream sensor out of the downpipe, and thread it into the upstream sensor location. The downstream sensor usually has enough length on its wires to reach the harness from that location. The downstream sensor is functionally identical to the upstream sensor - this means that it functions in exactly the same way - and it just has a longer wire. The downstream sensor also makes absolutely no difference - this means zero, or none - to how the engine runs. All it does is monitor the catalytic converter function, which you have none, so you will just be getting a cel for P0420 or P0421 or whatever soon enough anyway, whether the downstream sensor is plugged in or not.

Let's see how your engine runs with an O2 sensor plugged in to the correct location and we can take it from there.
 
Z
#14 · (Edited)
So I went and double checked. The upstream O2 is labeled correctly. For whatever reason, whoever did the swap decided to not keep the stock upstream O2 wiring run, and instead routed it the way that is shown in the pic.

The downstream does indeed connect right behind the DS taillight, I mislabeled it in the pic. It is the wire right above what I have labeled, which runs right behind the DS taillight.

Looking at the intake more, is the intake installed backwards? The longer run should be in front to smooth out airflow before reaching the MAF and as noted earlier the intake basically sitting atop the MAF. And the nipple should be behind the MAF...? Notice also in one of the pics, the wires for the MAF are completely taut. No clue how they got the plug onto the sensor.
 
#16 ·
So you have hacked up wiring for the upstream O2 sensor and you have P0135 and P0141 that usually tell you that the heater circuits for both sensors have failed but in this situation are quite possibly telling you that the ecm is not even detecting either O2 sensor - and you're hoping for what? A miracle to make your car run? Good luck with that. Get a scantool with live data capability and check the O2 sensor voltages. The upstream sensor should be bouncing up and down between 0.1 v and 0.9v every few seconds - else it is not working. The engine will not run right without the O2 sensors working correctly.
 
#18 ·
Ok, enlarge the pic that shows the MAF and look at the MAF. The nut you see under the corner of the MAF should not be there(quite possibly there is one on the corner we can't see). Remove the intake from the t-b to the air filter, then remove the MAF. Get rid of any "parts" under the MAF and re-mount the MAF, flush with the intake tube MAF mounting surface. Also, install a new a-f, as the one pictured is very dirty, which doesn't help things. If an OEM ECU is being used, start the engine and let it run a few minutes, then drive the car. Hopefully the engine will run better...hopefully.
Now, Mf-ster(sorry Mf-ster, I have to do this) is only trying to help, as he's done with many SC-ers. Sometimes he comes across a little agitated, but that's due to the many(too many) horror stories posted(some many times over) on SC. If you can do what he explains you try, you stand a very good chance of eliminating the problem-s that exist.
Good hunting.
 
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Z
#21 ·
Thanks! Those pics were taken without the greatest lighting so I'll have to give it a closer look and disassemble if I have time tonight.

As for MF, well, he can choose to participate in a congenial manner or not participate at all. I'd appreciate if he did, but I don't need to deal with a god-complex either, lol.
 
N
#23 · (Edited)
"Ok, enlarge the pic that shows the MAF and look at the MAF. The nut you see under the corner of the MAF should not be there(quite possibly there is one on the corner we can't see)". statement is incorrect. Here is a good picture that shows the shoulders that are built into the MAF mounting location. The MWR ones sort of look like nuts from certain angles. ZZe86 looks to have an MWR one but may be the first gen as it looks like the tube is curved.

Edited with the MWR picture.

Image
 

Attachments

#25 ·
Nstrout said:
" statement is incorrect."

View attachment 101308
Click to expand...
So correct ;)
The Cobb MAF tube I have has round "risers", and that "nut" threw me off. Still, the MAF in your pic does look to be angled, but can't tell for sure, not seeing it in the intake, removed from the engine compartment. My engine struggled until I discovered the injectors were "worn(the rubber seals)". After new Denso inj's were installed, the engine ran MUCH better.
Oh well, I hope you get it running better.
 
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Z
#26 · (Edited)
Had about 30min before taking the whole family to get our flu shots.

Took out the battery so I can replace the intake. Regardless of whether it's good or not I don't like how tight the wires have to go to reach the MAF. I figure I can put together a decent intake for under $100.

Cut away the zip ties so I can find proper locations for things instead of having things hang in the wind.

The upstream O2 was a bit worrying since it looked like it may have been extended. So I cut away the tape to examine it.
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Thankfully it was not. At least not in this portion. Hopefully no where else. That little bit of tape was just to hold things together I guess as I cut that away also.
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Doing some more basic trouble shooting, I decided to examine the fuses. And looky here! The EFI fuse was blown!
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Posting waiting for kids to be ready. Will try to get a fuse in there later and see how she runs!
 
Z
#27 ·
Ok, got flu shots, had dinner, had talk with son about sports and teammates. Put younger kids to sleep.

Found a 7.5a plugged it in, took off the intake and measured it (looks to be the right size, 2.5ish" ID). Didn't have any electronics cleaner to clean off the MAF so just stuck everything back in. Jammed the tube as close to the TB as I could and created some space for the filter but it's permanently deformed. Now that I write this I realize I didn't even inspect the MAF more thoroughly! 😵‍💫 Anybody recognize that intake? The filter end looks chopped off and is deformed also.
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The fact that the fuse was blown was bothering me. This is not something that normally blows so since it was all put together I had my son drive it while I looked at fuel trims and O2 voltage on my cheapo OBD reader.
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This is about 20-30min of putzing around. Still super hesitant and you can see why, it's running super rich. Upstream O2 seems to be working fine. I totally forgot to look at downstream O2.
 
N
#31 · (Edited)
This post was cross-listed under the thread I created. Not sure if you still needed help on this or if OP ever got the issue resolved but I helped my cousin fix his Spyder with a 2zz swap with almost identical issues.

It was the MWR intake that was causing the issue (edit - I see a few posts on here that were mentioning the MAF/Intake as well. Looks like MWR parts are of very poor quality.). The MAF mounting holes were too tall not allowing the MAF to sit completely flush. Filed down the mount holes and no more issues.
 
Z
#32 · (Edited)
Weird. I got a alert for Noobi's post but I don't remember getting alerts for the other ones. Or maybe I did and didn't bother replying. That MF'er was such a prick and he wasn't even close to being right, lol. Can't believe y'all be keeping him around.

But yeah, pretty sure the intake was messed up like Noobi's. A couple of folks were pointing out above how the MAF was sticking out a bit. I didn't bother trying to fix it though, just tossed it and made my own like how I said in one of the earlier posts. Been driving perfect ever since.

Anyways, doubt I'll be back on here. There are other platforms and not interested in "discussing" things with a gatekeeping MFer, lol.
 
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