PreviousOwner

I have a 1990 SR5 pickup with the 3VZE; I just replaced the timing belt, water pump and nine of twelve valve shims. Everything went back together well, the timing marks were on after two revolutions of the crankshaft, etc...I am nearly positive the cams and crankshaft are in time. After the engine warmed up it idled at about 3000 RPM and a timing light told me the #1 cylinder was firing at about 30 BTDC (with the jumper installed at the test port). Rotating the distributor to its limit brought the idle down to about 1400RMP and the timing light is now showing the engine timed to about 20BTDC. The engine is not throwing any codes. I did not put a timing light on it prior to replacing the timing belt.

My question is what input is the ECU using to advance the ignition (could I have missed a connection or crossed a vacuum line and caused the ignition to advance)? Is there some insight to the mechanical alignment for this engine before I pull the radiator and check the marks - repeating the same process with the same results? Should I have been using the harmonic balancer and front timing belt cover for TDC rather than the crankshaft and engine block marks?

Thanks.

millball

Check the TPS for function and proper adjustment.

Base timing is only apparent at idle (idle signal from TPS)

If the ECM thinks that the throttle body is off idle, it advances the spark timing.

PreviousOwner

I'm heading out to spend some quality time with Haynes and test the TPS. Thanks for the lead and I'll let you know.

MudHippy

If you don't have any codes then the TPS is idle circuit isn't causing a problem. It wouldn't be causing this problem even with code 51. Or without the check connectors jumped. The problem is the idle speed is too high. Fix that then work on your timing. Timing advances with engine speed. Regardless of any other conditions.

PreviousOwner

Well, these trucks are apparently idiot proof. While I was awaiting a replacement Air Intake Hose (just 71.18 from ToyotaPartsFactory.com!!) I stuffed some rags into the upstream side to keep out any FOD. After pulling the rags out of the throttle body the rig is running like new. Thanks Millball for leading me down the path to the TPS.

I will now try to delete this thread to regain some respect.

MudHippy

We all make mistakes. The thread is worth keeping in case someone does the same thing.

Just be glad you didn't suck anything further into the engine.

Turtl3

my father in law had a funny intake issue with his courier. it would idle fine and rev normally in neutral, as soon as he drove it, it would almost stall under load, lost a vast majority of its power, and this had us stumped for a while...silly bugger kept a rag in his engine bay for when he checks the oil...but he used to stick it near the airbox...it kept getting sucked in LOL! i also had a workshop make up some intercooler piping for a previous project of mine...they forgot to take the plastic dust caps out of the intercooler inlet/oultlet and proceeded to install everything and tighten all the clamps...lets just say im glad that the plug didnt get sucked into the turbo, or lodged inside the cooler