Hard warm start after intake manifold/injector work (1 Viewer)

[Rocket3004]

Hi all - hoping to get some input

This is on an 06 (i.e. VVTI). Prior to the following work, I did not have this issue at all. I recently took the intake mani/plenum off to repair the knock sensor harness. While the intake manifold was off, I figured I would have the injectors serviced by a local injector cleaning/rebuild shop. They were tested before and after cleaning. They weren't to shabby before hand, but were all within spec after with a good spray pattern after cleaning per the report. I put in a new IM gasket, new TB gasket, replaced a vacuum line, new PCV, and replaced one of the throttle body coolant lines - these lines/PCV simply to due age and hard rubber - they were fine before with no obvious cracks. I also used new OEM O-rings and insulators.

When I put everything together and started it up, I initially had a massive fuel leak from one injector spraying everywhere. Turns out I buggered one of the o-rings on install somehow. I pulled the rail alone, replaced the O ring, put the rail with new banjo bolt crush washers to the line feeding the other rail, and put it all back together. Fired up and runs great. It currently runs perfectly, minus the following issue:

These are all without priming the pump at all - key in, start.
Starting cold (i.e. overnight) - fine
Starting the car within ~30 mins of the shutting it down - fine
Starting the car between ~1hr and 6-8 hrs of prior run - it struggles but eventually starts with varying amount of lag.
If I put the key in and turn it to on and wait (once or multiple times) prior to start - if it is within that 1-6/8hr window of a prior run, it still struggles.

I've inspected all the fuel lines I removed for this job and around each injector - they are all bone dry no matter when I check them (cold start, while running, after shutting down and waiting an hour or so). I do not smell any fuel. Short and long term fuel trims are fine.

I don't think it is an external fuel leak bc the overnight start is fine (I assume it would struggle to start overnight if loosing pressure?) I don't think it is any of other components (like dampener/regulator etc) since I didn't mess with them.

After reading around (and thinking of what I messed with) this leads me to suspect it is an injector - maybe leaking when pressurized, causing some flooding and a hard start? After waiting overnight the leaky gas evaporates and it starts as normal for a cold start? This would be annoying since this would be a result of them being serviced. If this is the cause - how can I narrow it down to the specific injector? I tried looking through the spark plug hole with a cheap boroscope to see if I could see any pooling of gas or smell/see any gas on the plug tips but I didn't see anything and maybe smelled something, but pretty unscientific.

Looking for help and idea to diagnose this issue further. Pretty annoying that this is most likely a self inflicted issue... Thanks!!

 

[2001LC]

Leak down test, is easily done with fuel pressure tester. But I doubt this your issue. Since most common symptom of excessive FI leak down. Is long crank after sitting for awhile.

I assume you've not blocked OFF SAI system. Or have you?

Since this began, after you worked on. It's 90% chance issue created at that time, 10% other.
The 90%

• Coolant low, result in engine running very hot.
• Vacuum leak. Vacuum line off FPR, SAI, idle up control or other like those on IM.
• Damaged IM gasket during install (vacuum) leak. One bump on say, engine lift bracket, they get damaged/cut.
• Wire damage or wire housing block, such as VVT cam sensors. Those on sides of head next to IM, center top.
• Debris into intake ports, when IM removed.
• You can test each FI, by unplugging one at a time wire housing block, while running. RPMs should drop, a little at each as unplugged..

The 10% this may help. But I'd think issue would have been present.

Hot Engine Won't Start

I have an '05 LX that I recently purchased. I've been going through and fixing some minor issues along with some regular maintenance items. My biggest issue is that the truck doesn't want to start when the engine is hot. Symptoms: -Cold start, cranks right up -Warm engine shut off for ~10 min...

forum.ih8mud.com

 

[Rocket3004]

Thanks @2001LC . I was hoping you would chime in after reading many of your threads in the past. I have a similar approach - everything OEM and particular about the details.

Yes, the SAIP has been bypassed.

I agree - 90% chance it is something I interfaced with and that should narrow down my approach. I have gone through most items on the list
Coolant level is normal - I topped off after replacing the small amount I lost replacing the singe TB coolant hose
Vacuum leak I will have to double check. I agree that they can get buggered on the install. I managed to do that with one of the injector O-rings which seemed hard to do. It is a tight fit getting the IM into place.
Sensors in the vicinity - I'll double check the sensors, but on my inspection all connectors look seated... Also agree that they can be collateral damage due to fitment and jiggling the IM into place.
Intake ports - I vacuumed and cleaned the valley and surrounding region in several steps along the way during disassembly, blocked them off, and again prior to install, so hopefully this is a non issue.

I will say that I did have to gently bend the fuel supply line when taking the IM/fuel rail in and out to route it. It is not leaking nor frankly kinked. I assume that any damage there would lead to more than just an intermittent problem?

The car runs fine, except for the long-crank hot start which I think rules out many of the items, but still need to check.

I did some minor diagnostics - I pulled the coils and plugs, and placed rags/shop towels into the holes. I jumped the fuel pump as per the FSM and let it run for a couple of minutes and stopped. No external leaks I can see. I pulled the shop towels and noticed two things - after about 1hr Cyl 1 towel smelled strongly of gas, and Cyl 2 had a minor smell (not sure if they share any part of the plenum which would explain this rather than two faulty injectors). The others had no smell at all. I am not completely familiar with the fuel system, so I don't if this is just an anomaly of testing while the engine is not running, but this raises an eyebrow. I followed this up with hourly borescopes into the cylinders for about 3 hours after my pump run, and I swear I noticed a tiny bit of wetness along the edge of the intake valve on Cyl 1. The image quality is pretty poor so it is hard to say and didn't notice any frank drips, but again, at least raises an eyebrow. I manually turned the crank but didn't see anything more or less suspicious - just this finding.

I think I'm going to pull the drivers side rail and Cyl 1 injector to have it re-tested and/or replace it. I'll follow up unless @2001LC or anyone else feels strongly otherwise. It's not a bad job, and I have some extra o-rings, insulators, and banjo bolt crush washers anyways.

 

[2001LC]

Thanks @2001LC . I was hoping you would chime in after reading many of your threads in the past. I have a similar approach - everything OEM and particular about the details.

Yes, the SAIP has been bypassed.

I agree - 90% chance it is something I interfaced with and that should narrow down my approach. I have gone through most items on the list
Coolant level is normal - I topped off after replacing the small amount I lost replacing the singe TB coolant hose
Vacuum leak I will have to double check. I agree that they can get buggered on the install. I managed to do that with one of the injector O-rings which seemed hard to do. It is a tight fit getting the IM into place.
Sensors in the vicinity - I'll double check the sensors, but on my inspection all connectors look seated... Also agree that they can be collateral damage due to fitment and jiggling the IM into place.
Intake ports - I vacuumed and cleaned the valley and surrounding region in several steps along the way during disassembly, blocked them off, and again prior to install, so hopefully this is a non issue.

I will say that I did have to gently bend the fuel supply line when taking the IM/fuel rail in and out to route it. It is not leaking nor frankly kinked. I assume that any damage there would lead to more than just an intermittent problem?

The car runs fine, except for the long-crank hot start which I think rules out many of the items, but still need to check.

I did some minor diagnostics - I pulled the coils and plugs, and placed rags/shop towels into the holes. I jumped the fuel pump as per the FSM and let it run for a couple of minutes and stopped. No external leaks I can see. I pulled the shop towels and noticed two things - after about 1hr Cyl 1 towel smelled strongly of gas, and Cyl 2 had a minor smell (not sure if they share any part of the plenum which would explain this rather than two faulty injectors). The others had no smell at all. I am not completely familiar with the fuel system, so I don't if this is just an anomaly of testing while the engine is not running, but this raises an eyebrow. I followed this up with hourly borescopes into the cylinders for about 3 hours after my pump run, and I swear I noticed a tiny bit of wetness along the edge of the intake valve on Cyl 1. The image quality is pretty poor so it is hard to say and didn't notice any frank drips, but again, at least raises an eyebrow. I manually turned the crank but didn't see anything more or less suspicious - just this finding.

I think I'm going to pull the drivers side rail and Cyl 1 injector to have it re-tested and/or replace it. I'll follow up unless @2001LC or anyone else feels strongly otherwise. It's not a bad job, and I have some extra o-rings, insulators, and banjo bolt crush washers anyways.

SAI BLOCK OFF: So I don't know when, why, by whom or with what SAI blocked off kit. But now you've a modified systems. Some, I find wired to MAF we see MAF issues such as stall. These are not street illegal, and many have issues. Many are installed reacting to issues. Many of those have o2 extenders and compression issue. This is a rabbit hole, I'll not be going down. As I only do my filter mod, which keeps SAI working as designed (see link below).

One injector with some leak down, even dead. Would not likely result in hard, hot or warm start issue. Not even a long crank on cold start. When I pull a coil or FI wire from one of those. I don't notice a start issue. I just get a small drop in RPMs.

I could be the warm start unrelated, to IM work. We've issue with fuel pump in 06-07 when hot. Most found on hot days, after running in high RPM. Also there is fuel boiling issue, mostly 03-07. Overfilling gas tank and boiling fuel, CC then gets flooded. These CC then get worst and worst. They can cause start and running issues, mostly 20 or 30 minutes after warm up.

You need to make sure no coolant in any cylinder. You may need a better borescope. Some on Amazon for ~$100 reportedly have great res. One trick is to pressurized coolant system to about 17PSI, as you look.

S.A.I. Modification in VVT engines to prevent its failure! Alert Alert

We've a $2.00 part in the S.A.I.S. of the VVT engine, 1s taking-out ~$7,000.00 $15,000 (inflation) in parts. WOW! I've a very easy and cheap WORK AROUND. You are going to love this ;) This thread is dedicated to the 4.7L 2UZ-fe VVT engine, in the 2006 & 2007 100 series Land Cruiser & Lexus...

forum.ih8mud.com

 

[excessive]

that is a weird issue, especaully that the problem only appears after the engine is warm. Maybe do a vaccum leak smoke test or test with some starting fluid sprayed around the various parts you were working on.

 

[Rocket3004]

Quick update for future readers -
I did a smoke test, without any findings.

I took my suspected injector #1 back, and sure enough it was dripping. They re-cleaned it, put it a new filter basket. They couldn't offer an explanation how that happened despite the injectors being fine initially and testing fine after. I was tempted to have them all re-checked, but only brought in the one.

So far on testing, the car does not have the long-crank start up anymore. I have tested a few interval time periods without issue, but will try and update either way in the future.