jej3

Hello my fellow Football fans Thanks for the B00B pics that totally distracted me from my real post. This is a little long. Here's the cliff notes...

Car was running. Parked outside for a few weeks. Would crank, fire and die. Did a CE Panel cleanup and chased what I understand to be the usual suspects, need advice about next steps because I really don't want to have a SITM repeat this year.

Begin the longer version. I need some advice.....

I moved my 1990 out of the garage so I could remodel the garage over the Christmas/New Year's holiday. The Florida climate has been mild so no major issues. Battery was low when I started it to back out. I drove it about 5 miles just to wake her back up and then parked the car for a few weeks.

I went to start her back up a couple of weeks ago and there were all kinds of issues but essentially it would start, run, die. Flooring the pedal helped her fight for life but I couldn't feather the throttle at all to keep her running. There seemed to be no issue with relays - jumpered or not, same results. There were no ticking injectors, no lights on the the clear relay below the EZK/LH and no dancing RPM needles, nothing which proclaimed LH is no more.

I completely enlighted and confused myself reading all of the threads and decided I would just simply begin to do one of the things I intended to do for SITM this year.

I did a CE Panel refresh and replaced all fuses, inspected all relays, cleaned all grounds (except for one for drivers coil at engine block) and applied Deoxit and Stabilant to everything on the CE, all of the grounds and some other stuff that made sense (including EZK computer, 14 point connector, positive terminals at Jump Post, LH connection) I did grounds a year ago and there wasn't much to clean. The CE was quite clean and there was no sign of drips or corrosion from blower box.

I decided to pull both of the front sparkplugs on each side and check for spark when cranked. Check. Fuel on plugs from prior start attempt, check So I pulled the relay for fuel pump and started with foot to the floor. Sputter and die, fuel evacuated.

So I put the sparkplugs, which I replaced about 8-10K ago back in. I noticed the Quad Fire plugs had a healthy amount of black on the ends - kind of like they had been forced to run in a non-optimum environment (which I think SITM last year was for my car). IDK if this is normal but they seemed alot darker and sooty than they should be.

I got the car running and she's idling okay and then drops or hunts up and down. I also had an issue with the car acting like it was going to die under idle and then shooting off like it worked through bad gas or something. This behavior is erratic and best describe as erratic power loss under throttle or inability to return to idle without almost cutting out. I soaked the ISV in WD 40 and don't know if that changed anything.

This got me thinking about last year's SITM (which was equal parts fun and a little scary because of a somewhat similar issue) Car started giving me fits ( a little like it is now) when we were just outside of Banner Elk. As I drove up and down Beech Mountain with my two kids, the car would occasionally sputter and cough like it was going to cut out, we never did. And on the day we were to drive home, it began to start rough and we had to work hard to get to DR's and Jeanie's. I was the first one to their house, put a new fuel pump relay in and had only one blip in power on the way home. The relay I pulled in DR's words, "Looked like it lived a hard life" with some obvious load having been applied to the either 87 or 30 terminal (I forget which)

At sea level, I never had another issue. As I write this post, I think my current state and the SITM experience are related.

I have a list of things I'd like to do before SITM this year. Kids and I did TB/WP, belt/hose refresh last year. I should have pulled the trigger on new Plug Wires, Rotors and Caps but was just a bit low on cash.

I just went out in the dark and turned the key and she started on her own (no need to touch pedal), idled pretty steady and I looked for fireflies under the hood in the pitch dark. No sign.

So now, I'm wondering what you would do....

Chase the problem - which very well might be a bad 02 sensor or an aging MAF - especially if altitude was an issue

Or simply do the following items before SITM to see if the situation continues to improve...

1. Replace in take Fuel Pump with Fuel Strainer
2. Replace fuel filter
3. Reverse cycle Fuel Pump to be sure there are no "bits" in it
4. Order new plugs, caps and rotors, maybe plug wires, too
5. Do Top End Refresh (including replacing Temp II sensor and the ghetto wire which is clear gooped because the connector is broken)
5a. I guess sending injectors off for cleaning OR replacing with Ford injectors might be smart, too.
6. Check out all Vac connections
7. Possibly replace O2 sensor (seems like I maybe just should)


And other non-engine idle issues
8. Drain and Flush Auto Trans and Diff (I know this will have no bearing on
9. Chase AC issues OR just keep dumping refrigerant into her for an enjoyable 3 or 4 days of use.
10. Get the stereo in order for two kids that love the "Beastie Boys" and "Vanilla Ice" among the other current artists.
11. Pack the AAA card.

What would you do next to trouble shoot? I don't believe I have an LH on the way out, yet. But do think there could be some MAF or O2 Sensor issues. Anyone had similar issues related to their 02 sensor?

How far would you go with top-end refresh (i.e. what parts just make sense to replace and would any of them contribute to this issue)?

Now, I'm going to look for a thread on *****

Mrmerlin

you need to install the right spark plugs to start with try Bosch 7900.
New wires especially the coil wires,
remove the intank pump if you have one it probably failed.
inspect the knock sensors if the connectors are crumbling then you need new crank knock and hall sensors

Landseer

I'd also replace the ground strap at bat neg. with a new one.
Too many of these have died a slow death and contributed if not created some of the symptoms you mention.
A $7 round one from Advance Auto will do for now.

jej3

Thanks to you both for the info so far.

Mr. Merlin - I mis-spoke about my spark plugs, they are Bosch Platinum +4s that I purchased from 928 International.

Landseer - Sounds like your recommending I grab the inexpensive option from Advance Auto but I imagine I should ultimately go with a new OEM one????

I think I need to go find some 02 and MAF testing info because I'm just really thinking the change in altitude at SITM was a contributor.... am I chasing a ghost?

Mrmerlin

put the right plugs in,
use the silver tip Bosch 7900 .

the plus 4 or any other fancy plug isnt the best plug for the 928

jej3

I went to NAPA and got the Bosch 7900's and a 4-ga 15" battery cable. I know I'll probably want a 2 ga cable but I wanted to get something.

Replaced both and it struggled to idle until I believe it became acclimated. Idles smooth (no seeking up/down) but if I really get on throttle (shoot up to 4500 RPM) and let off, she almost dies.

I have new caps, rotors, plug wires and 02 sensor coming. All plugs seem pretty bad to me. Here's what one of them looked like (via my phone)....

jbrob007

Take this with a grain of salt since I know about as much as you, but I've heard multiple times on here that these cars run like crap on a less than optimal battery. A slightly low battery may not be the cause, but it sure will contribute to the problems, and the computers dont function correctly on a low battery.

WICruiser

I don't know much about those style plugs but it looks like it was very rich. The O2 sensor is a good place to start but check all of the fuel pressure regulators/dampers for any fuel in the vacuum lines. High vacuum at idle, or high speed lift off the throttle will suck a lot more fuel than the engine wants through a pretty small hole.

outbackgeorgia

Do all of the above.
If that doesn't fix the issue, it is most likely the LH.
I had exactly the same symptoms with my 87, went through all the steps, had a rebuilt LH so I " ruled out" the LH.
Wrong. Stranded on I75 south of ATL. (See avatar) After replacing the LH, no further issues and really enjoy driving the shark.
Dave

jej3

Please keep the thoughts coming everyone. Just wanting to have an excellent driving experience @ SITM this year.

Mrmerlin

hey bro you need to follow some kind of procedure and let us know what you have done.

otherwise everyone is just guessing at you problemmake a list of things that have been changed a nd let us know what still needs doing be thorough,

the answers you get will reflect how well you provide information

jej3

Good Advice. However, I thought I was pretty clear that I've only replaced the ground cable at battery and plugs so far. I'll certainly update this as I apply the new parts I said were coming (thus not put in).

My procedure is to deal with the Ignition system first and replace the caps, rotors and plug wires because I probably should have done that with the TB/WP last year but as I said in the OP, I was low on cash (thanks for making me say it again

I will then explore if there are any glitches in the fuel delivery as a result of a f&*ked up internal fuel pump by replacing it with the earlier strainer and putting on a new fuel filter, too.

I believe I indicated all of these steps in the OP. If it was less than clear, I apologize. There's no harm in having others comment on what some of the other contributing issues might be and, in fact, I appreciate the further comments by Jbrob007 (nice intake redo), WICruiser and Outbackgeorgia (I am thinking LH might be an issue but would prefer to knock off the things I know need to be done anyhow).

There are more No-Start, Rough Idle threads here than one can imagine. So forgive me for adding to the chaos.

Thank you MrMerlin for your comments. I look forward to you providing more as I offer more info.

BTW, unless my parents didn't tell me something I'm pretty sure I don't have a "bro" in Colorado

jej3

Time for an update...

I have now replaced the :

Sparkplugs - Bosch 7900
Wires - Factory Beru
Rotors
Distributor Caps
Battery Ground Strap - Using a 4GA 16" NAPA generic part

Decide while I was working to give the ISV a cocktail of PB Blaster, Brake Part Cleaner and WD 40 as a chaser

Upon initial ignition, car ran rough and had to give it the full throttle start treatment. It died a couple of times but I then simply turned key and idle fluctuated between 300RPMish and 900RPMish. Let it run this way for a minute and then manually worked throttle gently accelerating up to about 3000 RPM.

Got on and off throttle a few times, car would drop back down to practically cutting off and then come back with out cutting off

Soaked the ISV again with WD40 but chose to manipulate the vacuum to the intake by plugging the vacuum at ISV y connector. Sent WD40 down the ISV intake while still plugging and opening the end of the y connector which connects to the top of the intake. Idled smoother. When I got on and off throttle, I noticed RPMs wouldn't drop completely.

Exhaust and air around car smelled VERY rich. I think the car has been running rich for a while (at least since SITM last year) That would explain the quickly fouled sparkplugs and could possible explain the darkened terminal on the Fuel Pump relay that I replace at SITM last year (wouldn't it???)

Read this excellent post about disconnecting the 02 Sensor and Battery (https://rennlist.com/forums/928-foru...g-mystery.html)

I have now disconnected the 02 Sensor and if I read correctly, the LH has set 02 at a default mid-range setting. Is it harmful to drive with 02 Disconnected? I don't think so but I am getting a bit more confident that I'd like to give the car an "Italian Tuneup" with some fuel injection cleaner.

With the 02 Sensor disconnected there was practically no drop below idle when coming out of a high rpm. I believe the 02 sensor is certainly worth replacing. Anyone else had the "disconnected the 02 sensor and my car ran better syndrome" ?!?


Here is what I still very much intend to do....

1. Replace Fuel Filter
2. Replace internal fuel pump with the earlier strainer.
3. Replace 02 Sensor.

As I mentioned in my OP, I'm contemplating a top-end refresh but sooner or later cash starts running low. If I do go with a Top End refresh, EVERYTHING worth doing will be done, ISV, Knock, Hall, Temp II sensors, all vacuum lines, etc...

The car has 150K on it but the engine was completely rebuilt by the prior owner for $20K approx 55K ago. On the receipt, God bless that PO, I see they replaced the ISV, Hall Sender, Knock Sensors - what's the useful life of these items? Should I contemplate replacing these?

As a nice aside, the Torque Tube was also replaced about 50K miles ago.

I just want to get her running like she should Thanks for your help!

Any thoughts on other things I might contemplate?

jcorenman

Trey,

An observation (and not a criticism by any means): You've got three items still on your "to-do" list which are prime suspects. They are relatively simple to change, just do it and get them off the list. If it fixes it then great, if not then you can stop worrying and keep digging.

1. Fuel filter: They don't last forever, and if you haven't changed it (or have a receipt from a PO for a new one) then just change it.

2. And while you are there, drain the tank and pull the in-tank pump. With the ethanol in most of the fuel these days, there is zero chance that the rubber connector-hose is still intact. Replace it with the earlier strainer like you said.

3. O2-sensors don't last forever, typical change interval is 60K miles. Just change it.

The O2-sensor would actually be on top of my list. I think your problem is fuel-related (sooty plugs) and a funky O2 sensor will certainly do that.

Other possible issues:

Burned contact on the fuel-pump relay: That is independent, the pump runs all the time. It could indicate that the pump is drawing high current because it is periodically jamming on debris from the tank (the pump is before the filter), because of the broken intake-pump. But generally, when the pump ingests debris from the tank and jams, it stays jammed until it gets unjammed (e.g. run backwards and beat with a hammer) and then replaced.

But more likely that burned contact just indicates a loose/dirty relay connection that overheated. Dirty contacts have resistance, and resistance times current (squared) equals power, i.e. heating. Clean contacts are good. Unfortunately you cannot easily clean the female contact but give it a good eyeball.

It could also be a problem with the Temp-II sensor. This is the one at the front of the engine, under the cross-strut with two wires (one for LH and one for EZK). This sensor tells the brains how cold the engine is, so that the LH can add extra fuel during warmup. If it is telling the LH that the engine is cold, when it is not, then the LH will be injecting too much fuel. Check the resistance at the sensor and also at the LH connector, there is a good trouble-shooting guide in the WSM that lists the expected resistance. And remember that this sensor is grounded through its threaded fitting, if you remove it then skip the sealer and teflon tape, you need clean threads for a good ground connection.

It could also be a LH problem. There is a "hybrid" circuit in the LH that doesn't grow old gracefully, and gets replaced with a proper circuit board in rebuilt units. Symptoms vary, from the classic "clicking injectors" (and badly flooded motor) to just crappy running. Percentage-wise it's not a huge problem, but if the goal is a reliable road car then a rebuilt LH-- along with the in-tank fuel pump-- is on the short list of things that needs doing. (Alternately, find a good used one and carry that in the "road kit"). Louie Ott handles JDS Porsche rebuilt units, click here for info.

Good hunting!

jej3

Thank you, Jim. Very thoughtful reply. I appreciate it!

Car is going up in the air for the Fuel Filter, In-Tank Pump to Strainer conversion, and 02 sensor.

I'll report back later today (hopefully!)