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Discussion Starter #102 (Edited)
The plot thickens. The EGR ports on the block were relatively dirty, so I've since cleaned them. A quick fire of the engine proved exhaust gasses are reaching the valve.

After reinstalling the valve, I've found the exhaust gasses are coming out of the bottom port of the valve as they should. However, gasses are not exiting the MOD valve. I've triple checked my hose routing with the diagram under the hood and its correct.

To add to that, I placed my fingers on the EGR valve diaphragm and revved the engine. To my dismay, the EGR valve did not move.

So I think I have two problems. One being a bad EGR and two, a bad MOD valve. Could it be just a bad mod valve?

I also noticed no vacuum coming from the solenoid this is all hooked up to.

Edit: I applied vacuum to the EGR valve with the old mouth hole, and was able to verify the valve opens and closes. This makes me think either my MOD valve or the solenoid that operates it isn't working. Something on the vacuum side of things.
 

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I’d start by checking the solenoid valve electrically (and all the hoses running to/from it). Also note that on the modulator, you have the P and Q side - the P goes to the throttle body and the Q goes to the EGR valve. If you look at the modulator closely, you will see a small hump on the inside pipe - that’s the Q.
You can check the modulator with vacuum. If you remove it from the car, you should be able to blow from one nozzle through to the other (to make sure that the filter isn’t clogged). You can also do something similar with the VSV, by having the ignition on, and blowing through the top hose - air should come out the bottom hose and not through the filter on the top.
 

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Discussion Starter #104 (Edited)
Took apart the mod valve and the filter is clean. Also blew the the side ports and air did flow through. hose orientation is correct.

I don't have a vacuum pump at the moment, so I can't do more detailed testing yet.

I think the fault lies with the mod valve or solenoid, as I should be getting vacuum from the hoses leading up to it and I have nothing.

I think I'll start by pulling the hoses leading up to the solenoid and verifying vacuum. If I have vaccum reaching the solenoid but it's not operating, then there's my problem.

Edit: pulled the hose off the intake manifold and found that while it's pulling vacuum. The amount seems minimal.

Is there a quick answer easy way to test solenoid operation? think minimal tools
 

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Discussion Starter #105
I think the issue is low vacuum or a bad mod valve/solenoid. I have zero vacuum coming out of the solenoid (I was revving it to around 3500 rpm). In an attempt to defeat this, I ran the intake hose (that leads into solenoid) straight to the mod valve and still the egr valve refused to operate.

I know the egr system will not work without a vehicle speed sensor but I installed one and while my cel went away, I'm curious as to if the egr system is still inoperable.

While this is possible, I'd still think bypassing the solenoid would force vacuum to the egr valve and open it. Yet again, this is confusing as manually operating the egr doesnt stall the engine.

Something seems off in this whole cycle of garbage.
 

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if you manually open the EGR and it doesn't try to stall at idle, somethings still blocked.
 

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W9th the ignition on, have you checked to confirm that you have battery voltage going to the VSV wired connector??
 

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Discussion Starter #108
Yep. I've verified that I have 12 volts to the vsv wired connector.

By bypassing the vsv solenoid and hooking up the egr valve to the vacuum port that goes to the mod valve, I verified the egr valve still operates. So strike one is a bad vsv valve.

Strike two is that despite numerous attempts at cleaning the egr inlet port (that goes into the head), I still can't get the engine to stall by opening the egr. I've used hefty doses of carb cleaner and a wire brush and while tons of carbon came out, still no stall.
 

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tried starting it with the EGR valve out? will rev very high but will blow any carbon left in there out. You could still have stuff stuck in the head, it takes a fair bit to clean those passages out. I have had to use bits of wire to scrape the passages clear before.
 
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Try the VSV check as above, where, with the ignition on, if you blow through the top hose, air should come out of the bottom hose, and not out through the top of the VSV. But the VSV issue doesn’t solve the no stall (or perhaps not stall, but certainly a serous decrease in rpm) issue. It is not unusual to have to clean the passages in this circuit more than once - some have reamed this circuit out with a strong wire or similar, attached to a variable speed drill. Have you tried that? And as 2013GV says, after reaming, with the valve still off the car, start the car up. Only for about 2 seconds (or less). The engine will rev VERY high, and hopefully blow some loosened carbon out for you.
 

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Discussion Starter #111
I need to get a an attachment for my drill to run the wire brush through under power, but I have used thick metal tie wire and a ton of carb cleaner to get a fair amount of crap out. I've also started the car without the EGR and some more stuff came out, but obviously not enough to stall the engine when routing the exhaust gases into the inlet port. Based on feel, it seems I've cleaned the inlet port all the way to the end of the passage. However, I'm thinking the tiny ports that lead into the head are still clogged. I'll keep at it, but I'm getting sick of pulling the egr valve :D.

As for the VSV, I'll attempt that test tonight. I did do some pondering though. The FSM states the VSV will not operate without a working vehicle speed sensor. Since the sensor only works/reads under load, it stands to reason that the VSV won't actually open or pull much vacuum until the car is under load and moving. This could be why I'm not seeing vacuum exiting the vsv when parked?
 

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My FSM indicates that the VSV will open and work with the engine idling at 2000 rpm.
 

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Discussion Starter #113 (Edited)
Ah. I may have misread that portion.

Verified vsv is allowing air through the bottom hose. Unfortunately, the straw on my carb cleaner came off and is now stuck in the head egr passage. Not having much luck getting that out.

Edit. Got the straw out. Still no luck with clearing the egr inlet. I know the main passage is clean, but the ports going into the head must not be. At this point I'm over it. I've used three cans of carb cleaner in several different occasions, I know the main inlet is clear, and nothing is operating as it should. And I'm still not getting any operation of the egr valve with everything hooked up.

I really wanted to fix this, as I feel like the egr may be responsible for idle misfire and sluggish acceleration/bad mpg (20mpg city or highway), but at this point I'm admitting defeat.
 

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Excuse my laziness by not reading this entire post again. Can you do a recap of what you’ve done (other than the EGR circuit) to try to diagnose that misfire, sluggish acceleration and bad mpg? Normally, AFAIK, an EGR circuit that is not working won’t cause any of those issues....????
 

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Discussion Starter #115
No worries.

Aside from the EGR circuit, I've done the following:

-Replaced timing belt
-Repaired wallowed crankshaft key way and installed new crank timing cog (Torqued to 94 ft/lbs)
-Replaced CKP sensor inside of the distributor, as well as the cap and rotor
-Repaired crack in exhaust manifold
-Replaced O2 sensor
-Replaced wires and plugs (gapped to 0.028)
-Set timing and confirmed it's at 5* with the diagnostic plug jumped (Compression is 170 across all 4 cylinders when cold)
-Found a MIL/CEL light for VSS and discovered I had no VSS inside of my instrument cluster (must have been swapped at some point)
-Installed VSS (cleared codes and it has not returned)

Really the only issue I think I have left is a slight misfire at idle. The engine does seem rather loud (no ticking or anything, just loud) and can't maintain speed up a steady hill (going 60mph) without having your foot to the floor or downshifting and keeping it at 4500 RPM.

Bear in mind, I have 235/75/15 tires, a 2" coil lift, and a roof rack. Maybe this is the mileage and power I should expect with these modifications? Unfortunately, this car has had issues from the get go, so I don't have much to compare it against.
 

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Hmm....I suppose much depends on what you are comparing your car’s performance to. Frankly, when traveling on the highway, if I hit any kind of substantial hill, I’d have to downshift. Normally the rule of thumb is that your engine should be able to climb most inclines when floored in 3rd gear. But you are carrying a bit of weight, along with really heavy tires. I’m running the 235’s as well (no lift) and found that my local driving mileage was impacted at about 3mpg or so. It takes a lot of effort to overcome the inertia and move tires that are far heavier and bigger than Suzuki engineers thought were best for this car.
I’m not sure if I would go nutty chasing after the EGR stall test, either. Luckily, your federal 92 won’t throw the dreaded code 51 (nor will my 91). If the EGR was working properly, one of its benefits is that the valves will run a bit cooler, but there are those that disconnect this circuit altogether.
So, at least for me (and others may disagree), the misfire that you hear might be something you wish to diagnose further. I’d try to identify what cylinder is actually misfiring, and then change the spark leads to see if the misfire follows the lead, or stays with that cylinder. Have you done a recent compression test (since repairing the keyway, which does put a question mark on all of this) - it’s unlikely that every cylinder was exactly at 170psi....????
 

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Discussion Starter #117
As for mileage, that would stand to reason. I'm currently netting 21mpg all city or city with mixed highway. I have yet to do any all highway driving without hitting inclines or traffic. At the very least, I figured the 5.1 whatever gears in this thing would've helped more than they do. :D

As for the EGR, all of KickFix's warnings screamed that a malfunctioning EGR could cause limp home mode and various other issues. So I guess, that concerned me enough to try and repair it and in the process, I'd hoped it would maybe help with my issue.

My compression tester is missing the schrader valve (I remove it for health checks on my rotary powered car), so the highest reading we could catch with our eyes was one 170. It likely varied a little bit. If I can find that pesky valve, I'll give her one more go. I have confirmed the crank pulley no longer wobbles and verified it's still torqued to 94 ft/lbs.
 

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Your EGR valve is NOT connected to the computer - no wires, etc., that will give the ECU any signal from that circuit at all, unless your car is a California car (or your car is federal 94-95). Not all codes cause ’limphome’ or failsafe modes.
 

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as for the valve, go pilfer one from a tyre shop, its a standard "short" one, they will have hundreds in the rubbish bins.
 

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Discussion Starter #120
Your EGR valve is NOT connected to the computer - no wires, etc., that will give the ECU any signal from that circuit at all, unless your car is a California car (or your car is federal 94-95). Not all codes cause ’limphome’ or failsafe mo
That's good to know. For the time being then, I'll leave the damn thing alone.

I likely still have the schrader valve rolling around in my tool box but if I can't find it, I'll go pick one up.
 
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