Help with Timing on 88 Renix

Got an old jeep that wont pass smog, and my buddy said advance the timing to make the NOX go down. I marked the notch on the balancer, and and hooked up the gun to the number 1 cylinder wire. I started the ol xj up, and pulled the bolt from the distributor that connects to the block. It imediatley shot up, and started grinding. I had my buddy kill it. We tried to set it back in, but it does not go in all the way and stops with about 3/4ths of an inch left to go. We're pretty clueless now. Any help?

Probably won't go back down because the oil pump drive isn't lining up with the distributor shaft. Easiest thing is to look this up in your repair manual.

Ignition timing is not adjustable by turning the distributor. Now you've got to bring it to #1 TDC verified by rocker arm position or compression pressure and re-stab the distributor. Are you up to that?

As above. In case it's unclear, you must make sure that the engine is not only at TDC, according to the timing marks, but at TDC for cylinder 1. Since the engine goes around twice for one rev. of the distributor, if you get the wrong TDC, your distributor will be firing on the wrong cylinders and it won't run. If you don't have the facilities to check for which TDC you have, you can always try one, and if it doesn't work, turn the engine another rotation and try again. If you're lucky and get the indexing close enough, one or the other will work.

Remember that the helical gear on the distributor will rotate a little as you insert it, so start it a few degrees back from where you want it to end up.

In my experience with doing this on an 87, there are three potential working positions. If you get it one tooth retarded, it will start but stall on throttle. If you get it one tooth advanced, it may run well but will start hard.

As far as your NOX reading is concerned, your likely culprit is the EGR valve.

Damn seems pretty complicated. Thanks guys

Spearfisher XJ said:

Damn seems pretty complicated. Thanks guys

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It's more time consuming than complicated. You need to determine what point on the distributor body the rotor should be pointed at when at TDC for cylinder #1. Ideally, you would have marked this before pulling the distributor, but of course you didn't intentionally pull it. So you'll have to find at least which post of the cap is #1. Now you need to turn the engine to the correct TDC point by the timing mark. Now you need to determine where the slot in the oil pump should line up with the distributor when it's in the correct position, and turn the oil pump so that the tang of the distributor goes into it. Next, you start the distributor in, with the rotor a little bit offset from where you want it to end up (remember those helical gears), and if you're lucky, it will go all the way in, and the rotor will be pointing to the correct post. Now sock it down, and try the engine. If you're really lucky, it will run. If not, and if you know you got the right TDC point, you'll have to keep trying one-tooth variations until it does. Take a magic marker and mark the distributor with the location of the rotor on your first attempt, so that you can keep track of which way you're moving it on subsequent attempts.

It's not technically difficult, but with no marked off starting point, it might be frustrating and time consuming.

If you ever have to take off a distributor again, the rule is not to disturb the engine at all while it's out, and mark the rim of the distributor with the location of the rotor. If you do that, you can pop out the distro, fix it, etc., and drop it back in on the first try.

High NOX on an 88 tends to be related to a vacuum leak. The leak causes it to run hotter combustion temps and that is what generates NOX.

I had high NOX when I smoged my 88 4.5 Stroker, my smog guy told me that high NOX is either an EGR issues or a defective CAT. I checked my EGR and found that the Vacuum Transducer was not allowing the EGR to open. The Transducer requires 1 t0 2 psi of backpressure to open. I had installed a 2.5” cat pipe and 2.5” Flowmaster 50 this reduced my backpressure to 0psi except when I winged the throttle.
I cannot tell you how I passed smog but I will be going back to a 2.25 cat and the checking the backpressure.
You can check the backpressure vacuum/fuel pressure gauge by connecting it to the port at the base of the EGR. You can also check to see if the EGR is getting vacuum by connecting your vacuum/fuel pressure gauge to the port on the EGR side of the Vacuum Transducer. Check this site out and bookmark it http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm
Your buddy knows nothing about Renix so quit listening to him, sorry the truth hurts.
Good luck

kcjeep6 said:

I had high NOX when I smoged my 88 4.5 Stroker, my smog guy told me that high NOX is either an EGR issues or a defective CAT. I checked my EGR and found that the Vacuum Transducer was not allowing the EGR to open. The Transducer requires 1 t0 2 psi of backpressure to open. I had installed a 2.5” cat pipe and 2.5” Flowmaster 50 this reduced my backpressure to 0psi except when I winged the throttle.
I cannot tell you how I passed smog but I will be going back to a 2.25 cat and the checking the backpressure.
You can check the backpressure vacuum/fuel pressure gauge by connecting it to the port at the base of the EGR. You can also check to see if the EGR is getting vacuum by connecting your vacuum/fuel pressure gauge to the port on the EGR side of the Vacuum Transducer. Check this site out and bookmark it http://www.lunghd.com/Tech_Articles/Engine/Basic_Sensors_Diagnostics.htm
Your buddy knows nothing about Renix so quit listening to him, sorry the truth hurts.
Good luck

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Very interesting, this is one for the text book, on the risk of exhaust system mods if you need a DD that passes smog tests using an EGR!!!!!

One other cause of high NOX is carbon build up in the combustion chamber, which usually can be cleaned out with a seafoam or similar cleaning procedure.

There are a lot Utube videos around lately that might help bring you up to speed on "setting cyl #1 to TDC on the compression stroke" try searching the bold text with utube added to the search terms on Google.

You can use the harmonic balancer bolt head and socket-wrench tool to turn the engine crankshaft by hand, while cyl #1 spark plug is removed, use a flash light to look for a rising piston (two person job), then once you see the piston rising, put your finger over the spark plug hole as someone else turns the crank shaft by hand (or use a lab style rubber botlle stopper and see if it pops out), to see if air pressure is building under your finger (indicates that you have compression and not the exhaust stroke).

Ecomike said:

Very interesting, this is one for the text book, on the risk of exhaust system mods if you need a DD that passes smog tests using an EGR!!!!!

Click to expand...

Once I was able to get vacuum to the EGR my NOX went from 1650 to 325. I still need to address the backpressure issue, I am not sure how much of the exhaust system needs to be reduced to 2 1/4. I am going to start with the with the Cat then test the backpressure. If the Cat doesn’t do it I will have to work back, test at every step. I won’t be any time soon but I will post the results.