Downstream sensor(s) do not affect engine performance. All they do is monitor the converter(s).

Fuel pressure and leakdown needs to be checked at the fuel filter outlet.

Distributor: no check engine light with P1345 in memory means the distributor is meshed correctly with the cam gear. It also means camshaft retard is within ~13 degrees, it needs to be 0 degrees +or- 2 degrees. Best to have it checked and adjusted if necessary to eliminate crossfire in the cap.

 

ok sounds good i ordered 2 denso 234-4012 o2 sensors today but they will not be here for about a week i will try to do the max pressure test this weekend

the cam adjustment should be able to wait until after i get the misfire fixed since it ran fine before?

i was planning on getting an alignment before this happened so i would rather get both done while i'm there.

 

Camshaft retard can be off ~13 degrees, which is huge, and not set P1345, but you will have misfires, guaranteed.

 

ok i probably should have guessed that
i will have to figure something out though because the way it runs i don't think i can drive it anywhere to get that done and the scanner i have access to will not read that

 

Ok I know it's been awhile but a I got stuff done today

Rechecked vacuum lines broke a rubber elbow replaced it everything else looked good

Max psi test hit 80psi held pretty good
Replaced fuel filter while I was there

Replaced both upstream 02 sensors
Ran new fuel trims

At idle. At 2k rpm
B1
Stft 0. 50
Ltft 6.2 21
B2
Stft. 0. 1.5
Ltft. 5.4. 1.5
Map 12.9. 10.3
Spk adv 20. 36
Iat. 80. 80
Maf. .77. 2.2
02 b1s1
V. .2. .5
%. 50. 50
B2s2
V. .2_.8. .4_.7
%. 0_-1. 0

Also I put in a bottle of chevron techron like you said

 

All of the short, and long term fuel trims were positive?

 

They jumped around a bit but Yeah didn't really see any negative numbers

 

She's running lean.
1. Inject propane or carb cleaner spray directly into the MAF at the air box connection and see if the oxygen sensors respond, (voltage must increase).


2. Prop the throttle open at ~1500 rpm, (couple of business cards or so) between the throttle linkage and the stop screw. Then disconnect the IAC, (idle air controller) so the PCM can't control idle speed. Using propane, look for vacuum leak(s). Idle speed will increase if/when you hit a vacuum leak. Check along the intake gaskets where they meet the heads. Pull the PCV valve out and inject some into the valve cover. Check the PCV valve itself, might be broken or stuck open. Kink off the power brake booster line and see if idle speed decreases. Also, really need to get all four numbers on the fuel delivery system and post them: https://blazerforum.com/forum/2nd-ge...eakdown-88305/

 

Ok ran the tests you told me to

Fuel psi
At service port
Key on engine off 62 psi
Dropped to 55 psi held for 10+ min

At fuel filter
Key on engine off 80 psi
Dropped to 73 psi held for 10+ min

Propane at maf 02 sensors value changed

Iac unplugged engine ran at 1600 rpm by itself
Tried propane all around intake and in pcv port on valve cover no change at all

Tried pinching brake booster line no change at all (iac was still unplugged )

 

Connect the scan tool and display live data. With the engine idling at normal operating temp, (200F), trans in park or neutral, all accessories turned off, PCM in closed loop operation: Post all values, (idle speed, fuel trim, fuel cell number, ignition advance, MAP, MAF, TPS, BARO, ECT, IAT, etc, etc, and camshaft retard if the scanner will access it). Anything it shows, post it