Mike Frye

Hey Scott,

I agree with Ken, first order of business is to dial up the idle screw to get it to stay running.

I have a couple of questions.

1. Have you done a pressure test on the intake since you put everything back together? and
2. Do you have a blink'r to test the CO level now that you've adjusted the MAF to 380?

If you still have any vacuum/unmetered air leaks in the system you're not going to be able to move forward and get a smooth idle.

I assume since you said that it was set to 380 that you changed it from whatever it was before (did you take note of the previous reading?) The adjustment on the MAF may have been changed by someone else to compensate for a tired MAF. The manual says that 380 is a starting point to getting it dialed in (if it can be). Once you get it idling, plan on adjusting that until you get a good reading on the CO as well as the idle. A bad MAF can cause some strange running issues but until you go through the setting/adjustment procedures in the manual you won't know if yours is bad or just a little out of calibration. The MAF is a wear item and over time it definitely requires rebuilding. If yours hasn't been done, it probably should be if for no other reason than to rule it out as a factor.

Do some searches on adjusting the idle as well as adjusting the CO and pressure testing and you should find lots about it.

Pfc. Parts

Hi Mike -

I did do a positive pressure test before and after the refresh using Dwayne's method (adventures in plumbing). It held 1.5lbs positive for about 5 seconds then the test apparatus blew off the MAF. I considered that a passing grade. I wasn't patient enough (and also lacked the strength) to suck all the air out of it with a mighty-vac for a negative test. There must be a better way to do that.

I have a blinkr and used it prior to the intake refresh. The MAF was originally set to 380 when I began working with the blinkr, I was never able to get it to blink with the bad intake. Before putting the MAF back in I reset it to 380 and I haven't begun tuning it again yet. I can't remember where I put the darned blinkr thing, it's somewhere in a drawer...

Pfc. Parts

That did it Ken. Adjusted the idle CCW about a turn, cold start perfect, no stall on throttle off.

She's back!

Thanks to everyone. It's going to be a fun end of the summer. Next stop Laguna Seca in November!

Pfc. Parts

Of course, the real next step is a transmission refresh, but first I have to replace the turbo on my wife's Audi. The 928's been hogging the rack so long I think she's forgotten she owns it. She bought it from a mechanic last year, a '98 1.8T in great condition, the fellow had just replaced the heads after a timing belt failure but she blew the exhaust seals after driving it for a couple of months. Turns out two of the three bolts that mounted the turbo to the exhaust manifold had backed out and the third sheared off leaving half the bolt stuck in the turbo.

My next trick will be removing the turbo, extracting the bolt and replacing it. Should be fun after 6 months refreshing the 928 intake but you guys may not hear much from my end for awhile

Pfc. Parts

Here I thought I was out of the woods.

Mike I didn't much want to hear this, but now I suppose I'll need to bite the bullet. After declaring victory earlier today I made the mistake of actually driving the car (well, not really driving. I took it from the top of my driveway and back again. Almost a half mile). The results weren't all that good.

Even after performing Ken's idle tune on the throttle (greatly appreciated though it was), the car has no power. It starts very nicely now and doesn't stall when I take my foot off the gas, but it also has trouble running up a moderately steep hill and it vibrates badly when I step on the gas hard. It was easy to discount this while it was on the rack but as soon as I put it on the road (or more correctly the driveway) it became apparent I hadn't really fixed the problem.

My first thought was my cats had gone bad. Not out of line since the car is 30 years old and has never had them replaced. It only has 62K on it but I've been told the ceramics get brittle and fail over time even when not drivien. I had a '96 Ford Bronco with bad cats and it drove a bit like this; no power at all, like it was gasping for breath all the time. A mechanic told me I needed a new transmission and I put one in but it later turned out to be the catalytic converters.

It might still be the cats.Since the car isn't subject to emission controls I might pull them just to see, but after reading John Speaks' write up on MAF failures and their symptoms I'm inclined to replace the MAF first. I have a spare and it's easier than replacing the cats. It runs, but it's absolutely gutless and I believe that's also consistent with a MAF failure. It would also explain why I couldn't get Ken's Blink'r to work, though that may have been caused by the vacuum leak as well.

I've already moved my wife's Audi to the rack so it may be a few weeks before I can test this theory but it's certain we won't be attending the Pebble Beach Concourse this week. Sigh.

Mike Frye

Scott,

Yup, the idle adjustment Ken suggested was just a way of getting it to keep running long enough to get everything else adjusted. Next you will have to work through the part of the manual where it tells how to adjust the CO and idle. These are related. You should also verify timing with a timing light at idle, off idle and at WOT (or at least the first two). These will also confirm that your TPS is working. If you can get a fuel pressure gauge it would be good to verify pressure at the rail and you should also verify that each one of the injectors is getting voltage using a noid light. It won't say whether they are doing anything when voltage is applied but it's a start. IMO those should have been replaced as part of the refresh too, but that train has left the station.

I think the MAF rebuild/replace is just a requirement at this point in the age of the car regardless of miles and it will give you another 15+ years of good service. It also eliminates a whole range of strange symptoms that you won't have to attribute to the MAF once you have a known good one.

Landseer

Did it run well prior to intake job?

If so, maybe doublcheck firing order if you had plug wires off.
Also remove distrib caps and clean the contacts carefully by just barely touching them with dremel wire brush.
Be sure the coil wires are seated, ends of coils are not corroded, wires not nicked or badly routed, use mirror to check the corrosion part.

Not trying to dispute the MAF refresh, its just that I had those issues with 32V cars that sat in garage during other work. Similar symptoms.

SMTCapeCod

ALright, where'd this go???

I recall fighting a similar battle on my '85 long time ago, don't recall whether the solution was vacuum leak or fuel...but it wasn't difficult once I found it.

Now my 86.5 is having some slight symptoms- 2-3 seconds of starter before lighting off, sag in idle immediately afterward. It's not bad yet but its vexing me.

Pfc. Parts

It hasn't gone far yet

I swapped out the MAF from my parts car (which runs better than the street car but looks like something the cat drug in). No Joy. I believe I've ruled out the MAF.

I just received a fuel pressure gauge and plan to test the pump next week. I was very unhappy to find I couldn't buy an adapter to connect a standard gauge (Amazon) to the M12x1.5 test port on the rail. I'll likely spend a day or so finding the right hose I can use to clamp the pressure gauge to the rail. At this point I believe I have a fuel pressure problem since I've replaced the intake and ignition systems already. It might still be a bad coil on the passenger side since I didn't replace that.

Pfc. Parts

Well, 4 weeks later I got time to install the pressure gauge on the fuel rail. No joy again, the gauge shows a standard 2 bar at idle, peaking around 2.4 bar with an open throttle.

Since I've replaced the intake and the ignition and fuel pressure checks, I'm down to injectors and harness. I have a universal noid light but can't figure out how to pull the injector connectors off without removing the intake. Any suggestions?

Pfc. Parts

Just to update this thread, after putting an inductive timing light on ech plug wire I found a bad connector on cylinder #2. After correcting that the engine does run better, but it still isn't running right; it has a very noticeable shake between 1000 and 3000 rpm under load. The power is better, but it still sounds and feels like its missing.

My next step will be to pull the plenums again and check the injectors. I believe I have a stuck injector or a bad injector connection somewhere.

Pfc. Parts

After working through the air/fuel/spark diagnostic routine I narrowed the possibilities down to fuel. I hooked up a pressure gauge to the passenger side rail using one of Greg's adapters and the pump checked out at a steady 2 bar at idle peaking to about 2.7 under throttle. That left the injectors, which I couldn't really believe since I'd tested each of them before re-installing.

That just goes to show how useless the pre-installation test was; 2 of the 8 injectors were stuck. I replaced them with a couple of good injectors from my parts car after putting new filters, O rings and pintle caps on them and the car runs like a sewing machine (a sewing machine with a very deep voice

Thanks to everyone on this list for helping me through the intake refresh, the car is running like new. Next stop, Laguna Seca in November!

Regards,