When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
This one scares the hell out of me, since on a built motor still tight, you should be seeing pressure in the 35-40 PSI range instead.
Figure with the engine was built, the oil pump releif valve was stronger sprung to gain some more oil pressure as the motor is spun up, instead of blown off (Melting 10295 oil pump).
The fact that the oil pump is geared directly off the crank shaft (under drive pulley will have nothing to do with the speed of the pump), this is screaming that either some of the motor journals on now on the loose side, and where the motor is loosing pressure, or the pump relieve valve is not fully closing (some RTV in it) and at the least, the oil pump will need to be pulled to clean the releif piston and channel instead.
So as stated, start off with someone that can go over the motor!!! With any luck, it's just the oil pressure sensor reading off/ low that a actual analog pressure sensor can determine that the senor itself is not reading correctly, instead of the motor having low oil pressure itself (and internal problems instead).
It's been cooler here the last couple days, in the 80's and the motor has stayed cooler, engine temp has stayed around 190 and oil pressure has stayed around 24-25PSI. It was when it was 95 degrees that it hit 230 degrees and 16PSI. The motor heats up extremely quickly though, within 3-4 minutes of starting the car the temps are shooting to the upper 100's. Never had a car get hot that quick.
I had the damn check engine light come on again and reduced engine power. It went off before I was able to get a code last time, I'll go in the morning if it's still on and have them put it on a reader.
My FI C6 will show low oil pressure at idle after a few hard pulls...it's common. When the engine rpm's increase the oil pump spins at high rpm's as well which cause's cavitation and oil foaming. Thus the drop in pressure at low rpm's/idle.
Coolant temps at 230-240 at idle (or under 30mph) with FI is common as well on hot days if you are running the ac. There is a recent thread in the FI section regarding this issue. If it occurs with ac off verify your fan is running at at the appropriate speed so it's cooling the engine at idle.
Backfiring could be several things but may be due to a bad cam sensor. Although often with a bad cam sensor it will usually "hard start" as well as backfire.
Lastly if a CEL came on at one time, the code will most likely be stored and can be read with a CAN bus obd II code reader.
History is only half the battle, he's still battling his oil pressure demons. I'd say that unfortunately he might have to dig into the engine.
I would be afraid of driving the car with oil pressures and temps so erratic. Hoping for a quick fix.....
Figure with the engine was built, the oil pump releif valve was stronger sprung to gain some more oil pressure as the motor is spun up, instead of blown off (Melting 10295 oil pump).
The fact that the oil pump is geared directly off the crank shaft (under drive pulley will have nothing to do with the speed of the pump), this is screaming that either some of the motor journals on now on the loose side, and where the motor is loosing pressure, or the pump relieve valve is not fully closing (some RTV in it) and at the least, the oil pump will need to be pulled to clean the releif piston and channel instead.
The oil pump is a good place to start. The build would not be the first to have an error in R&R of the oil pump and low pressure as a result. Unfortunately, if the builder of the car saw this and let it go, it doesn't provide confidence about the rest of the workmanship.
OP, did you discuss any of your concerns with the guy from West Texas Motorsports? What did he say?
I asked him about the low oil pressure and he said it had been "fairly low" since they got it" and when he installed the cam he put the aftermarket oil pump on it at the same time.
As for the check engine light, I got the following codes.
P2135 was the current code
P2544 was in the history
On the tubing running into the throttle body, I can very easily just slip off the connector by hand. Here are pics
With it on
With it off, that can't be right that I can easily slip the off.
Overall engine pic
Overall engine pic
Last edited by matt03Z06; Sep 12, 2015 at 11:10 AM.
The pictures aren't good enough for me to really see what side of the engine you're looking at. It looks like there are two issues.
1. You're missing a clip that holds that evap line on to the intake
Since you don't have a supercharger that connection is never under any significant pressure, so I don't see it flying off or anything. But, it could still vibrate loose. It will be a significant vacuum leak without it connected.
I'd just order a new tube (comes with clip). Advance I think has some replacement clips but since you don't have one to compare to it's probably easier to just get a new one. They're cheap.. like $10 from GM
2. Is there anything disconnected in any of those pictures on the passenger side of the engine? If I'm seeing what I think I'm seeing, the barb just after the throttle body isn't hooked to anything. That is bad. That would cause a massive vacuum leak. Or, maybe it's just capped off. I can't tell.
Last edited by schpenxel; Sep 13, 2015 at 10:23 PM.
If the barb you are talking about is in the second picture, yes it is unhooked. In the first picture it is hooked up. That is on the drivers side of the engine. I can remove the line from that barb with little effort, like all I have to do is move it off with my finger, and with how the motor rocks I could see it coming loose very easily. Check engine light went off again and hasn't yet come back on. Could that be causing it to throw the throttle body code?
Barb problem would cause a lean condition, since if the hose pops off, will allow air around the Maf (nstead of throught it) that was un-sensored into the intake manifold.
P2135 Throttle Position (TP) Sensor 1-2 Correlation ECM
With the code your getting, screaming loose connection/problem with one of wires for the TB, or maybe TB itself if ported caused problems with the TB position sensor instead (if the unit was fully pulled apart when ported).
Being an intermittent problem, leads me to believe a wiring connection problem instead.
