Timing will not advance, ECU and crank show different readings

[duck95]

I was just fooling around with my timing light the other night. I changed the timing light inductor to #4 sparkplug wire and pulled the trigger. The timing light was not firing at the same rate as the #1 or #3 plug. Even #2 plug was firing intermittently compared to #1/#3. I thought maybe my coil/wire/ect was going bad. I swapped plug wires and the problem stayed the same. So I went out and bought a new coil and installed it. Same problem. I put an oscope on the cam angle sensor and got a square wave, it was a clean signal, but would shift every so often. I did the same with the iginitor signal. That tells me that the CAS is good. I put the engine at TDC with the cam gears and crankshaft mark lines up with the TDC indicator on the crank. So I actually "checked" my timing. It was at 0 degrees btdc even atdc (first mark closest to firewall or first mark on the right side. My data logger said 8-9 degrees btdc. I grounded the ecu and the data logger said 5 degrees but the engine with timing light indicated it was lucky to even be at tdc. The car has felt like a slug lately and my vacuum at idle is about 16.5" on good days. My engine isn't the healthiest, my rings have a little blow-by. Why does my ecu and physical indication not match? Is my knock sensor bad? I don't have a CEL. I have a pot installed in series with the barometric pressure sensor, but it is turned all the way to 0 ohms. Any help is greatly appreciated. This car seems to be a constant headache. Good one of course. DSM's are supposed to be that way, right?

 

[steve]

Understand the the ECU doesn't know the real timing. It expects you to synch it's input to the actual by adjusting the CAS until the actual timing is 5* BTDC when the timing connector is grounded. On a 1G you can't do this with a datalogger connected becasye grounding the mode pin on the DLC while the timing connector is grounded actually set the ECU into BISS adjustment mode not timing adjustment more. I'm not sure what it does on a 2G since they really didn't have adjustable sensors.

Steve

 

[duck95]

Thanks for the reply, Steve. That's the thing, I've got a '95 that has no adjustable CAS. The ecu is setting the timing, but the crank indication and OBD2 datalogger do not agree on what the timing is. I've changed a couple things since last post. I screwed my biss all the way closed, my idle didn't change and my vacuum went to 17.5" and a few days ago I changed back to BPR6EIX from BPR7ES. I'm going to try and change back to the colder plug. Any thoughts it will help!

 

[duck95]

Come on, somebody has had to have this problem before! I changed my sparkplugs to the 7's and no difference. I had backed out the obstruction in the maf a while ago, but had put it back right away, but I turned it in 1 turn to make sure it was in enough. The car's timing is great at startup when cold, but it goes downhill from there. I hooked up the logger and found my LTFT was at 12. So I increased my fuel pressure (yeah I know, wrong fix for the problem. A person needs bigger injectors if fuel pressure needs to be raised). It brought my LTFT down, but the timing was still retarded to essential zero, and atdc. Also my biss is all the way shut. I'm running on empty here, I need some good ideas, please help!

 

[luvmygst]

I would unplug the battery and let the computer reset, and then see what changes. What is the base timing at idle? My 95 runs about 5-7 deg at idle with no ac on. I see about 21 deg max at 15 psi on the logger.

 

[duck95]

Thanks for the reply mygst, I tried what you said. My LTFT reset, but the car still timed at 0 btdc and even atdc. My logger says it is @ 5 degrees while grounding the pin and then it says 5-10 degrees when at idle @ 750 RPM. But the physical crank says that it is 0 degrees! I have no adjustment because of having no adjustable cam angle sensor. WTF! I have a 1g CAS sitting in the slot, it is just not wired up.

 

[duck95]

Shameless Bump!!

 

[duck95]

Mods, please move to Problem Diagnosis.

 

[duck95]

Ok, can anyone tell me this. Which way should your cam lobes point when the car is at top dead center on cylinder #1. Mine seem to be pointing in the same direction, toward the back of the car. That doesn't seem correct to me. Can anyone tell me different?

 

[talonracn49]

It depends on where in the cycle you are. A four stroke engine will have the pistons at TDC twice, once on the power stroke, and once on the end of the exhaust/beginning of the intake stroke. Remember is take 720 degrees of rotation to see all four strokes.

Where should your cam lobes be? Depends on where in the cycle you are.

 

[steve]

The dowel pins on the cams indexing the cam sprockets at as 12 o'clock when the engine is at TDC. Unless the cam is twisted that serves to identify the difference between TDC for cylinder 1 from TDC cylinder 4 (when the dowels point down)

Steve

 

[duck95]

Thanks for the replys. I've even gone to Satan and talked to their "top techs" about what is going on. And the saying "you get what you pay for" goes for advice too. Free advice from them didn't help. I did go out and check again to see if everything lined up. My lobes were actually pointing at each other, towards the center of the engine. And like before, my cam gears line up, dowel pins are at 12 o'clock, and my crankshaft markings line up. I tried finding true TDC using the old screwdriver in the cylinder trick, trying to find out when the piston stops rising. Judging from what I felt, it is off about 1 tooth, but how can a person know that its so close to right. But when I start the engine and start logging timing advance and use the timing gun that's where it starts becoming apples and oranges. Timing gun says 0-5 degrees, logger 10-15. I've found that grounding the ecu pin, sets the timing at exactly 5 ATDC, logger says 5 BTDC, exactly 10 degrees off. So I've narrowed it down to three things. Either I jumped a tooth on the belt which appears very difficult to assertain, I have phantom knock or I could need new sparkplugs wires. But if I had phantom knock, wouldn't the ecu know that the timing was being retarded and the logger would show the actual timing being set? The car runs good, idles @ 750-800, doesn't overheat, just very sluggish on the low end and not much umph on the upper end. Also, I'm getting terrible gas mileage. I put in a new denso o2 sensor about a month ago. I haven't really been able to make it through a tank of gas normally yet so I don't know if it made a difference. I'm ready to take the car in to either Satan or the area's tuner shop and have them go through it. Does this info make it as clear as mud?

 

[steve]

You sure your timing light isn't one of the advance types and not set to 0.
Have you tried another just to make sure?

Steve

 

[duck95]

Funny you should ask that, because, yes I do have a timing light with advance. I checked it this morning on my way out the door. The dial was turned to about maybe 2-3 degrees. Maybe that makes a big difference? Don't know. I'll borrow a simple timing light from work today a try that also. That's a great find Steve, thanks. Should I try replacing sparkplug wires next if this doesn't work?

 

[duck95]

Well, Steve I would give you rep points but I see you really don't need any! I started the car up, let it warm up, and then turned the timing gun on it. It timed at about 5 btdc. That's great. However, I drove the car around last night for about 15 min, the car got up to actually running temp. I checked the timing then at idle, it was about 2-3 btdc, still highly retarded. So now my next plan of action is, what is causing my timing to be retarded. Knock, high intake temp, bad iav, or ? I recently changed the oil and put in some Restore, that's kind of when the problem started, maybe it's coincedence. You can watch my vacuum/boost gauge change when the engine messes with the timing. The needle will change slightly. I'm running about 16 inHg at idle, not good. My timing needs to go back up. Any suggestions? Also, what will retard your timing, exactly?

 

[duck95]

Well, I had my cylinder head redone. I definetly had leakage through my valves, they were not seating all the way. Valve and seats ground, replaced valve stem seals, had the head decked, new factory head gasket and head studs, new cam seals, the whole nine yards. Car started up great, ran great. My vacuum increased slightly at idle, it's about 17.5", which is what i was looking for. I did a boost leak check on the intake manifold. I have a small leak, it's pretty slow. But compared to what I used to have, it's like being sealtight. But there is still something that don't make sense. Why is my timing still being retarded? I timed it with it being fully warm it is about 2* BTDC. I've confirmed it with two guns. Do I have a bad knock sensor? That's next on the list to replace. After all the machine work I had done, why do I still have this?