After valve cover gasket change did test ride. Engine started and car ran fine initially for test drive. After about two miles the rpms dropped to near zero and the engine had no power. It could not climb a mild grade. No throttle response. Had to have towed home.

TPS OK and and power check to MAF OK. The engine will start but has a very low and rough idle like there is a massive vacuum leak or it is getting minimal fuel. It will stall after a minute or so. All hose are connected and there are no cracks. Wire and connector inspection looks good. No engine check light. All lights extinguish when the engine starts.

A scan tool is on the way but I wanted to throw it out there for ideas in the mean time.

Reg

 

Sorry didn't notice I had no signature.

The car is a 1999 626, V6.

 

ok you car has jumped timing probably 2 or 3 teeth it hapend to mine and is probably a resolt of oil on the timing belt

 

Hooked up a scan tool. No codes found.

Skipped a few teeth. Hmm. What is the valve to piston clearance? Zero? Am wondering if I have done any engine damage.

Reg

 

Pulled the manual and looked up timing belt replacement. Another day under the car.
The annoying thing is I replaced the valve cover gaskets to eliminate oil leaks and the timing belt is all but new.

Thanks Man for the advice. I wonder if there is an easy way to do this without the all out disassembly of a normal belt replacement? So long as the belt is not damaged all I need to do is lift the belt, set the timing and clean up any oil.

Reg

 

If your timing belt is almost new, you're probably OK unless the installation was screwed up. For peace of mind you can strobe the engine if you want, but a timing issue big enough to do this would set some codes and a flashing CEL (misfire).
Are you sure your air intake is OK, i.e. filter clean, no hidden cracks in the duct between the air filter and engine?
If they're good, spark and fuel are next. If you have serious ignition issues, the ECU will not start the fuel pump, so make sure you have good spark and didn't cross connect your plug wires. Once that's clear, the next thing I would look for is fuel pressure regulator. If you misconnected anything there you can get wrong fuel rail pressure and even starvation. How do you even know for sure if you have good vacuum?
As far as engine damage goes, Mazdas have +ve clearance engines, so even if the timing belts break, pistons will not hit valves.
My suspicions suggest you screwed up reconnecting after the valve cover job, and either omitted or cross-connected some wiring or (more likely) plumbing.
Don't have high hopes for your OBD code reader either. If the basics aren't in the ballpark, it might not even initialize, furthermore unless it's a pretty good one, they are of very limited usefulness for all but the simplist cases.

 

Thanks Old,

Lots of good suggestions. Appreciate it.

My Actron CP9180 scanner came in yesterday. I hooked it up to the car. No codes active or stored. Had it run a diagnostic. Lots of OK's. It is saying nothing is wrong.

At least electrically things are fine. Sort of does leave the timing as suspicious. Odd though that it occurred when it did as the car was under deceleration. I also know all wires and fuel pressure was correct because the car did start and run just fine for a mile or two. Wouldn't do that with crossed wires or bad vacuum.

So wiring is fine. No error codes. Fuel pressure to the injectors. No audible (bad) manifold leaks.

Looked up my maintenance log on the car. The timing belt has 39,000 miles on it. Not so new. The installation was not the best as the dealer replaced it when I made them replace a leaking water pump. Paid them but they weren't happy. Later my garage found the timing cover bolts loose. But again that was nearly 40,000 miles ago.

Plan to rotate the engine and look at the timing belt and marks. Something somewhere failed catastrophically.

Keep the suggestions coming.

Reg

 

Lots of possibilities but possible plugged converter. Did the plug holes have oil in them? Did you remove the plugs and spray something in them to clean them out? Were the plugwires fried from oil contamination? Feel for exhaust pressure out the tailpipe or create an exhaust leak. Bang on the main converter and listen for rattles.

 

No oil in holes. Plugs not removed. Plugs and wires replaced 30,000 miles ago.

 

Could be the timing belt (tho' the miles are low for that). If the dealer was such a slob that he left the timing cover loose, there's a good chance he didn't do the idler/ tensioner/ tensioner spring replacement protocol properly (if at all). This could easily result in premature belt issues or cog jumping.