milisakeracing
New Member
Just like Coxy-Lexus in another post in this section, I am experiencing the same symptoms. At the moment the engine runs very rough, is much louder than usual, and when I unplug the air flow meter it makes no difference to the engine RPM. And at idle it seems to be a bit out of balance, almost sounds like a loping V8. It also seems to have barely any power, and puts out a fair bit of vibration.
This problem just appeared overnight, one day it was running fine, then the next time I started it it was doing this. In between starts I had repaired a couple of leaks. Here are the details of everything starting from the beginning:
4/13
I had replaced the o-ring on the module which goes to the thermostat but it appears that when I installed it, the o-ring did not slip all the way into place and became pinched, eventually rupturing and causing some of the leaking down the side of the engine as well as into the valley (will be a big clean-up job for the underbody of the car, especially around the adapter plate and bell housing of the transmission where much of the coolant ran down out of the valley). This time I cleaned up both the module and the hole where it press fits into since there was corrosion evident on both and also applied water pump/coolant rated silicone RTV to the area where the ring would seat on the module.
Last, the o-ring on the hard line which press fits into the back of the water pump housing was finally replaced. This was a known bad gasket. It had torn during the original installation and I did not have a spare at the time, only some handy silicone gasket maker. This area was cleaned, a new o-ring fitted, and again some water pump/coolant rated silicone RTV was used on the area.
Although this work has finally solved the leaks, it seems to have generated a new problem. After reassembly of the lower and upper intake manifolds and all other supporting components and wire connections, I now have what almost seems like a miss but not quite. The exhaust note sounds different, with the note change seeming to originate from the passenger side of the engine, possibly even at the cylinder by the firewall.
I thought at first it might be the spark plug wires and when I checked, the first wire I pulled left its electrode on the spark plug. The internal wires practically disintegrated into grey powder! Upon replacing the wires with a new set, the problem still exists. Next I am going to start pulling plugs on the passenger side. I already pulled the plug which had the faulty spark plug wire and it appeared to be ok, but this is closest to the front of the engine and the new note does not seem to be coming from the front.
Power seems to be nearly the same with roll off happening maybe slightly lower in the rpm range than before but it could just be in my head and the different exhaust note playing games with what I feel, acceleration-wise.
Would an injector not firing, or firing too long produce this result? How about a plug not firing? I thought at first it was an exhaust leak up near the manifold but there are no significant leaks around the area (can feel a small amount of leakage around the exit of the manifold where it joins the exhaust pipe) and this new condition only started happening after removing the LIM and UIM. I have also pulled the codes from the ECU but the three existing codes are ones which have always existed (27, 29, 42), nothing new found here which would help diagnose the problem.
I have been over the manifolds and all wiring and hose connections to them and have not found any issues yet which is why I am bringing this to the forum to get some input from others who may have suggestions I have not checked yet.
Well, looks like I was too quick to judge that there was a noticeable reduction in power. This morning when I got in the car to drive it to work it really did not have much power at all. Just kind of chugged along. Reminds me of when the spark plugs went bad in a previous car I had so I'll be checking those first once I'm out of work today and done with stuff around the house tonight.
4/14
Further troubleshooting results. Replaced the plugs this evening. At least one of the plugs was definitely bad. It's gap was way out and it appears the seal around the body had lost its integrity. I'll post pictures of them tomorrow.
By the sound of it, I am not sure replacing the plugs fixed the issue. Idle and exhaust note still seems off. Checked all connections once again around the intake manifolds and everything appears to be connected. Also checked that all fuel injectors were firing by feeling the bodies of the ones I could reach and for the ones I couldn't reach, listening to them through a screwdriver touched to them.
Unplugged the AFM and there was no change in idle or sound. Unplugged the TPS and the car died. Unplugged the cold start injector and there was no change in idle or sound. While unplugging the cold start injector harness I did feel what felt like cool air moving past my fingers. Thinking of pulling the LIM and UIM tomorrow and using some non-hardening sealant on the gasket surfaces plus the metal gaskets and reassembling to see if this fixes anything.
4/15
Another update, tore down the LIM and UIM again today and triple checked everything. Good news is I didn't leave any shop towels in the intake runners or openings in the heads, lol. Bad news is after reassembling everything, the car is still chugging and low on power.
Tomorrow I will be checking compression on all cylinders and also taking off the dizzies to take a peak to see if they're corroded or broken. I'm getting spark and fuel so not sure what the problem is still. Codes still remain at 27, 29, and 42 which are non-issues.
4/16
Ok, checked compression and in doing so checked the coloration on the plugs as well. Found something interesting. As seen in the picture album in the following link, plugs 2, 3, 5, and 8 are showing they have been run extremely hot while the others remain normal coloration. 2, 8 and 3, 5 are on opposite banks but on the same dizzy. Correlation?
http://picasaweb.google.com/1uzsupra...eat=directlink (Picture names will tell location and cylinder numbering for the plugs and dizzy)
Cylinder pressures in PSI on cold engine. All plugs are out and the throttle plate is in WOT position (btw, cylinder pressure held in key off position):
1 - 170
2 - 170
3 - 175
4 - 165
5 - 177
6 - 165
7 - 175
8 - 175
This problem just appeared overnight, one day it was running fine, then the next time I started it it was doing this. In between starts I had repaired a couple of leaks. Here are the details of everything starting from the beginning:
4/13
I had replaced the o-ring on the module which goes to the thermostat but it appears that when I installed it, the o-ring did not slip all the way into place and became pinched, eventually rupturing and causing some of the leaking down the side of the engine as well as into the valley (will be a big clean-up job for the underbody of the car, especially around the adapter plate and bell housing of the transmission where much of the coolant ran down out of the valley). This time I cleaned up both the module and the hole where it press fits into since there was corrosion evident on both and also applied water pump/coolant rated silicone RTV to the area where the ring would seat on the module.
Last, the o-ring on the hard line which press fits into the back of the water pump housing was finally replaced. This was a known bad gasket. It had torn during the original installation and I did not have a spare at the time, only some handy silicone gasket maker. This area was cleaned, a new o-ring fitted, and again some water pump/coolant rated silicone RTV was used on the area.
Although this work has finally solved the leaks, it seems to have generated a new problem. After reassembly of the lower and upper intake manifolds and all other supporting components and wire connections, I now have what almost seems like a miss but not quite. The exhaust note sounds different, with the note change seeming to originate from the passenger side of the engine, possibly even at the cylinder by the firewall.
I thought at first it might be the spark plug wires and when I checked, the first wire I pulled left its electrode on the spark plug. The internal wires practically disintegrated into grey powder! Upon replacing the wires with a new set, the problem still exists. Next I am going to start pulling plugs on the passenger side. I already pulled the plug which had the faulty spark plug wire and it appeared to be ok, but this is closest to the front of the engine and the new note does not seem to be coming from the front.
Power seems to be nearly the same with roll off happening maybe slightly lower in the rpm range than before but it could just be in my head and the different exhaust note playing games with what I feel, acceleration-wise.
Would an injector not firing, or firing too long produce this result? How about a plug not firing? I thought at first it was an exhaust leak up near the manifold but there are no significant leaks around the area (can feel a small amount of leakage around the exit of the manifold where it joins the exhaust pipe) and this new condition only started happening after removing the LIM and UIM. I have also pulled the codes from the ECU but the three existing codes are ones which have always existed (27, 29, 42), nothing new found here which would help diagnose the problem.
I have been over the manifolds and all wiring and hose connections to them and have not found any issues yet which is why I am bringing this to the forum to get some input from others who may have suggestions I have not checked yet.
Well, looks like I was too quick to judge that there was a noticeable reduction in power. This morning when I got in the car to drive it to work it really did not have much power at all. Just kind of chugged along. Reminds me of when the spark plugs went bad in a previous car I had so I'll be checking those first once I'm out of work today and done with stuff around the house tonight.
4/14
Further troubleshooting results. Replaced the plugs this evening. At least one of the plugs was definitely bad. It's gap was way out and it appears the seal around the body had lost its integrity. I'll post pictures of them tomorrow.
By the sound of it, I am not sure replacing the plugs fixed the issue. Idle and exhaust note still seems off. Checked all connections once again around the intake manifolds and everything appears to be connected. Also checked that all fuel injectors were firing by feeling the bodies of the ones I could reach and for the ones I couldn't reach, listening to them through a screwdriver touched to them.
Unplugged the AFM and there was no change in idle or sound. Unplugged the TPS and the car died. Unplugged the cold start injector and there was no change in idle or sound. While unplugging the cold start injector harness I did feel what felt like cool air moving past my fingers. Thinking of pulling the LIM and UIM tomorrow and using some non-hardening sealant on the gasket surfaces plus the metal gaskets and reassembling to see if this fixes anything.
4/15
Another update, tore down the LIM and UIM again today and triple checked everything. Good news is I didn't leave any shop towels in the intake runners or openings in the heads, lol. Bad news is after reassembling everything, the car is still chugging and low on power.
Tomorrow I will be checking compression on all cylinders and also taking off the dizzies to take a peak to see if they're corroded or broken. I'm getting spark and fuel so not sure what the problem is still. Codes still remain at 27, 29, and 42 which are non-issues.
4/16
Ok, checked compression and in doing so checked the coloration on the plugs as well. Found something interesting. As seen in the picture album in the following link, plugs 2, 3, 5, and 8 are showing they have been run extremely hot while the others remain normal coloration. 2, 8 and 3, 5 are on opposite banks but on the same dizzy. Correlation?
http://picasaweb.google.com/1uzsupra...eat=directlink (Picture names will tell location and cylinder numbering for the plugs and dizzy)
Cylinder pressures in PSI on cold engine. All plugs are out and the throttle plate is in WOT position (btw, cylinder pressure held in key off position):
1 - 170
2 - 170
3 - 175
4 - 165
5 - 177
6 - 165
7 - 175
8 - 175
