Rough idle after partial engine overhaul

I finally got my truck running by replacing the crankshaft position sensor with a new OEM one but its idling very rough and slow (around 500 rpm). In the video I posted I think it would have kept running but I turned it off to prevent potential damage since it was shaking more than I'd like.

here’s a list of things that I addressed during the overhaul:
-Valve adjustment
-Cleaned air intake manifold, throttle body, MAF (new gaskets for everything)
-Replaced oil pump gasket and front main seal
-Replaced distributor o ring (new spark plugs, cap and rotor)
-replaced oil filter housing o ring
-new gaskets, insulators, spacers for fuel injectors (also cleaned in ultrasonic)
-rebuilt starter
-replaced all tubes that looked cracked

Now that it's running I plan on renting a timing light to see if it's just the timing that's off a hair.

I've heard of some weird things happening after people clean out components of their air intake system but most of them experience a high idle from what I've read.

Anyways, if anyone has had any experience like this or knows what direction I should go please let me know.

 

out of curiosity, what happens if you put the old cap/rotor back on

2rz crank, no spark (solved) | Tacoma World

 

Check for spark at each plug wire then double check each fuel injector connector, make sure they click and have a positive feel when the go on.

 

I put the old cap back on and it seems to be idling at a normal rate around ~1000rpm but it’s still shaking a decent amount like in the last video.
I gave it a little rev this time so that might have done something too

I checked for spark at the first plug but I haven’t done the rest. I’ll check them out next

 

If you have smoke machine I'd check gasket leaks around the injectors

even dumbass me screwed that one up.....there was an extra seal/gasket stuck down in one of the injector holes I missed

a cracked injector cup(very unlikely) the injectors set into would do the same

 

I actually installed new injector cups and all the gaskets/spacers associated with the injectors. I would like to avoid removing this much before addressing some of the easier to access parts. It's a good idea though.

I broke the nipples off the power steering air control valve thing and decided I would just clamp the tubes shut to simulate a vacuum. Obviously not the best but I noticed even doing that made the truck run a lot better. The new part is coming tuesday so I'm going to replace any other suspect vacuum lines i may have damaged just from removing and reinstalling.

 

update:

I bought a timing light and determined that timing is 5 degrees BTDC right within the 3-7 degree spec.

I did a fuel pressure test and found that at idle it's ~41 PSI, however once I turn the car off it drops to 0 PSI in about a minute or so. I know it should maintain about 21 PSI for 5 minutes but I don't know how to interpret this result. There aren't any obvious leaks around the filter, rail or regulator. The regulator is also a known good part since I swapped it into my other tacoma to double check. Not sure if this is just a shitty autozone gauge that loses pressure right away.

 

Assuming no CE light?

I changed my dizzy O ring….stabbed dizzy in one tooth off. Would start for 10secs then die b4 I realized installed wrong
But u stated timing looks good

I took OldSilver’s advice and splurged on a LCE FP gauge
My 214k fuel pump reads 46lbs running and stays above 40lbs for 30-45mins after shut down

injectors u said ultrasonic’d
How many miles?

Sometimes putting old injectors in a vibrating solvent just loosens miles of debris…then when FP added, just blocks injectors

Guessing fuel pump or dramatic loss of pressure after shut down could point to leaking/clogged injectors

Look into MotorWest
$100 to RM 4 injectors 5day turnaround
One of mine was so bad, had to buy a core
Only $25 for MW!

 

last night I decided I’m going to try to install a permanent fuel pressure gauge because it’s something that would be helpful to have. I don’t trust the autozone one I rented. Parts are coming in today. I’ll try to document what I’ve done if it works out.

last time I did a similar overhaul I used MW and really loved their service. I should have just done that when I had it all apart but I thought I’d save some money now that I have an ultrasonic.

this car is new to me so I’m assuming they have around 250k miles on them like the rest of the truck.

 

I also forgot to mention that I’m getting some misfire codes as of yesterday. A random misfire and a misfire on cylinders 1 and 3. These last few weeks I didn’t get one at all and then I tried to adjust the throttle body position sensor while the car was running and it ran worse and those P0300 codes came up.

 

I once did an overhaul and forgot to connect a groundstrap behind manifold. It gave me so many random problems. Double check that sh**.

 

Good suggestion but I've already got that covered. I've cleaned the connection and reattached the ground straps on the engine block, from the head to firewall and from the battery terminal.

Let me know if there's one I'm missing.

 

If you have a scanner, look at the stft and ltft. If its negative beyond 15% your injector could be leaking which also explains why psi goes to 0 so fast.
If the % is positive is calling for more fuel so clogged injector or intake manifold leak likely.

 

Thank you. This is really helpful.

I decided to send out my injectors to motor west for a professional cleaning since I have a few signs pointing to faulty injectors.

If it still runs rough when I put her back together I'll try to get a reading from my scanner.

 

I'd like to thank everyone for their advice. Feels great to be back on the road.

I got my injectors back from Motor West and now she's running smooth as ever.

I think that CarControl was right in his assumption that using the ultrasonic on my injectors probably just loosened debris and they immediately reclogged with fuel pressure.

Moral of the story ...Don't try to clean your injectors yourself unless you plan on flow testing them as well

 

EXCELLENT NEWS!

 

Here is my LCE FP gauge

I have used the readings 3 times already to rule out issues with fuel pump

 

Looks really clean. I have the pieces to build a gauge where the fuel line meets the fuel rail. I might go with the LCE since it's relatively affordable and anything that I could put together might fail on the highway haha

 

I made FP gauges on my 2 other old cars
But relatively simple bc of the rubber hoses on both. IIRC, our fuel inlets are steel and near firewall.
I decided too much of a chance to screw something up and bit the bullet for that LCE gauge