Poor starts, very low idle, stalls out?

HAROLD FARRELL

MEMBER
1989 CHEVROLET VAN
5.7L
V8
2WD
AUTOMATIC
115,000 MILES

Had it serviced: ofl, removed and replaced the transmission fluid, and filter. Removed and replaced leaking AT cooing lines. Removed and replaced the oil pressure sensor and installed a new oil press. Gauge press 5/35# with no engine noise. Requested clean, remove oil/fluids build up on motor/wires, etc, from seeping head gaskets/coolant and leaking/ oozing ps unit and pump/ fittings. Note: Engine ran fine previously. Reputable Owner/ top mechanic for decades-age 62- did and has done work on my van and jeep for 3 years, no previous concerns. Note: he went on vacation, left his son-30s/service Mgr."in charge", and youngest mechanic /of 3 years-21-state " needs new engine, 'nothing more we can do" spent $1,098.00 aforementioned work service. I plan a conversation with the owner ASAP. Thank you all, much appreciated.

Tuesday, September 5th, 2023 AT 3:46 PM

1 Reply

JACOBANDNICKOLAS

MECHANIC
110,114 POSTS

Hi,

The oil pressure, although on the low side, isn't out of specification, especially at a low idle. (See pic below)

When you have a low idle and stalling issue, in most cases it is the result of an engine vacuum leak. Check to see if you can locate any.

Here is a link that explains how to check:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Next, the engine idle speed is controlled by an idle air control valve (IAC). If this is dirty or the air passage into the throttle body it uses is excessively dirty or partially plugged, you certainly will have starting issues and idle problems. If there are no vacuum leaks, I would next try to service the IAC. Here is a link that explains how it's done. Note: It is located on the throttle body. (See pic 2)

https://www.2carpros.com/articles/idle-air-control-valve-service

When you remove the IAC, make sure the port it is removed from is clean. I say that because when your foot is off the throttle, the throttle plate completely closes off air. The IAC is what allows air to enter the engine so it can run. It also is responsible for increasing the idle speed when a load is placed on the engine such as the AC is turned on, or a load from the power steering pump.

Try these two things and let me know what you find. BTW, if there are no engine noises, the engine is likely fine.

Take care,

Joe

See pics below.

One additional thought. Scan the computer for codes. This has an OBD1 system and all that is needed to retrieve codes is a short jumper wire. You can even use a paper clip. Follow this link:

https://www.2carpros.com/articles/buick-cadillac-chevy-gmc-oldsmobile-pontiac-gm-1983-1995-obd1-code-definitions-and-retrieval-method

Images (Click to make bigger)