where to start ?
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Laughing Gas
Joined: Aug 2010
Posts: 1,098
Likes: 6
From: Ventura co.
where to start ?
well, Like i said a few months back. my truck is starting to start hard and missing until warmed up then runs fine. as far as i know these are the original glow plugs. i drove it around and checked the temp on the on the exhaust ports. cylinder 1 is running about 40 degrees colder by my lazer heat gauge. this is a texas truck no gpr so i just cant check the glow plugs like the cal truck. so i am thinking one of three things is happening. Bad glow plug, dead cylinder, or bad injectors. I have AE but only have fooled around with it. what do i need to look at with AE. how do i or can i check the compression while changing the glow plugs ? truck has about 240.000 on it. is this a normal thing that happens with a bad glow plug ? i have no leaks so if i put in new injectors do i need to replace the cups ? Thanks..
Hotshot
Joined: Mar 2014
Posts: 10,750
Likes: 1,065
From: Douglassville, PA
All trucks have GPR except for CA trucks and chassis trucks, which have a GPCM. AE cannot tell you anything about your glow plug system. You can ohm out your glow plugs through the UVCH connections at the VC. Two outer pins on each end of the connector on both heads are the glow plug pins. The GPR sits slightly to the left on top of the engine about midway back. When the engine is cold you can test the large lugs for power with the key on as long as the PCM has the glow plugs activated. That's up to two minutes depending on temps.
More Turbo
Joined: May 2015
Posts: 670
Likes: 13
From: Nampa, ID
The quick and dirty way to rule out a severe compression problem is to check the blow-by and listen to it while cranking.
the blow-by test is simple. Take the oil fill cap off while the truck is fully warmed up and running. You will see some white smoke/vapor coming out. This is normal for a 7.3. What you don't want is pressure escaping. If you flip the cap upside down on the oil fill spout, it should slowly vibrate off, not get blown off by the pressure.
listen to the truck while it cranks. Does the cranking speed have a fast spot? A fast spot is a low compression cylinder that takes less effort for the starter to push.
since your miss clears up when warm, I'm willing to bet you don't have a severe compression issue. I would lean more towards glow plugs, GPR or injectors. If an oil change with synthetic oil improves your startup and miss, it's probably injectors.
the blow-by test is simple. Take the oil fill cap off while the truck is fully warmed up and running. You will see some white smoke/vapor coming out. This is normal for a 7.3. What you don't want is pressure escaping. If you flip the cap upside down on the oil fill spout, it should slowly vibrate off, not get blown off by the pressure.
listen to the truck while it cranks. Does the cranking speed have a fast spot? A fast spot is a low compression cylinder that takes less effort for the starter to push.
since your miss clears up when warm, I'm willing to bet you don't have a severe compression issue. I would lean more towards glow plugs, GPR or injectors. If an oil change with synthetic oil improves your startup and miss, it's probably injectors.
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Laughing Gas
Joined: Aug 2010
Posts: 1,098
Likes: 6
From: Ventura co.
starter spinning at the same rpm while cranking. cap is not blowing off.
I ordered New glow plugs from Clay yesterday.
while i was at it, I ordered a new billet compressor wheel to get rid of my surge when towing. a turbo rebuild kit and pedestal install kit..
I run Rotella T6.
I will be taking a good look at the under cover wire harness while im in there.
and then if i need to save up some cash, i will install new injectors. mine do seem real loud and kinda tinny as i would call it.
I ordered New glow plugs from Clay yesterday.
while i was at it, I ordered a new billet compressor wheel to get rid of my surge when towing. a turbo rebuild kit and pedestal install kit..
I run Rotella T6.
I will be taking a good look at the under cover wire harness while im in there.
and then if i need to save up some cash, i will install new injectors. mine do seem real loud and kinda tinny as i would call it.
Lead Driver
Joined: Dec 2006
Posts: 7,092
Likes: 145
From: San Diego, CA
Sounds like mine (and most other) 7.3Ls out there.
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